Bicyclic aza compounds as muscarinic M1 receptor antagonists

ABSTRACT

This invention relates to compounds (Formula (1)) that are agonists of the muscarinic M1 receptor and which are useful in the treatment of muscarinic M1 receptor mediated diseases. Also provided are pharmaceutical compositions containing the compounds and the therapeutic uses of the compounds. Compounds provided are of formula where R 1 -R 5 , X 1 , X 2  and p are as defined herein.

RELATED APPLICATION INFORMATION

This application is a continuation of U.S. patent application Ser. No.:15/595,107, filed May 15, 2017, now U.S. Patent No.: 9,975,890, which isa continuation of U.S. patent application Ser. No.: 14/996,829, filedJan. 15, 2016, now U.S. Patent No.: 9,669,013, which is a continuationof U.S. patent application Ser. No.: 14/428,927, filed Mar. 17, 2015,now U.S. Patent No.: 9,266,857, which is a 371 national stage ofInternational Patent Application PCT/GB2013/052442, filed Sep. 18, 2013,which claims the benefit of U.S. Provisional Application Serial No:61/823,606, filed May 15, 2013, and of U.S. Provisional ApplicationSerial No.: 61/702,330, filed Sep. 18, 2012. The entire contents ofthese applications are incorporated herein by reference in theirentirety.

This invention relates to a class of novel amide compounds, their salts,pharmaceutical compositions containing them and their use in therapy ofthe human body. In particular, the invention is directed to a class ofamide compounds, which are muscarinic M1 receptor agonists, and henceare useful in the treatment of Alzheimer's Disease, schizophrenia,cognitive disorders and other diseases mediated by the muscarinic M1receptor, as well as the treatment or alleviation of pain.

BACKGROUND OF THE INVENTION

Muscarinic acetylcholine receptors (mAChRs) are members of the Gprotein-coupled receptor superfamily which mediate the actions of theneurotransmitter acetylcholine in both the central and peripheralnervous system. Five mAChR subtypes have been cloned, M₁ to M₅. The M₁mAChR is predominantly expressed post-synaptically in the cortex,hippocampus, striatum and thalamus; M₂ mAChRs are located predominantlyin the brainstem and thalamus, though also in the cortex, hippocampusand striatum where they reside on cholinergic synaptic terminals(Langmead et al., 2008 Br J Pharmacol). However, M₂ mAChRs are alsoexpressed peripherally on cardiac tissue (where they mediate the vagalinnervation of the heart) and in smooth muscle and exocrine glands. M₃mAChRs are expressed at relatively low level in the CNS but are widelyexpressed in smooth muscle and glandular tissues such as sweat andsalivary glands (Langmead et al., 2008 Br J Pharmacol).

Muscarinic receptors in the central nervous system, especially the M₁mAChR, play a critical role in mediating higher cognitive processing.Diseases associated with cognitive impairments, such as Alzheimer'sdisease, are accompanied by loss of cholinergic neurons in the basalforebrain (Whitehouse et al. 1982 Science). In schizophrenia, which isalso characterised by cognitive impairments, mAChR density is reduced inthe pre-frontal cortex, hippocampus and caudate putamen of schizophrenicsubjects (Dean et al., 2002 Mol Psychiatry). Furthermore, in animalmodels, blockade or lesion of central cholinergic pathways results inprofound cognitive deficits and non-selective mAChR antagonists havebeen shown to induce psychotomimetic effects in psychiatric patients.Cholinergic replacement therapy has largely been based on the use ofacetylcholinesterase inhibitors to prevent the breakdown of endogenousacetylcholine. These compounds have shown efficacy versus symptomaticcognitive decline in the clinic, but give rise to dose-limiting sideeffects resulting from stimulation of peripheral M₂ and M₃ mAChRsincluding disturbed gastrointestinal motility, bradycardia, nausea andvomiting (http://www.drugs.com/pro/donepezil.html;http://www.drugs.com/pro/rivastigmine.html).

Further discovery efforts have targeted the identification of direct M₁mAChR agonists to target increases in cognitive function. Such effortsresulted in the identification of a range of agonists, exemplified bycompounds such as xanomeline, AF267B, sabcomeline, milameline andcevimeline. Many of these compounds have been shown to be highlyeffective in pre-clinical models of cognition in both rodents and/ornon-human primates. Milameline has shown efficacy versusscopolamine-induced deficits in working and spatial memory in rodents;sabcomeline displayed efficacy in a visual object discrimination task inmarmosets and xanomeline reversed mAChR antagonist-induced deficits incognitive performance in a passive avoidance paradigm.

Alzheimer's disease (AD) is the most common neurodegenerative disorder(26.6 million people worldwide in 2006) that affects the elderly,resulting in profound memory loss and cognitive dysfunction. Theaetiology of the disease is complex, but is characterised by twohallmark brain sequelae: aggregates of amyloid plaques, largely composedof amyloid-β peptide (Aβ), and neurofibrillary tangles, formed byhyperphosphorylated tau proteins. The accumulation of Aβ is thought tobe the central feature in the progression of AD and, as such, manyputative therapies for the treatment of AD are currently targetinginhibition of Aβ production. Aβ is derived from proteolytic cleavage ofthe membrane bound amyloid precursor protein (APP). APP is processed bytwo routes, non-amyloidgenic and amyloidgenic. Cleavage of APP byγ-secretase is common to both pathways, but in the former APP is cleavedby an α-secretase to yield soluble APPα. The cleavage site is within theAβ sequence, thereby precluding its formation. However, in theamyloidgenic route, APP is cleaved by β-secretase to yield soluble APPβand also Aβ. In vitro studies have shown that mAChR agonists can promotethe processing of APP toward the soluble, non-amyloidogenic pathway. Invivo studies showed that the mAChR agonist, AF267B, altered disease-likepathology in the 3×TgAD transgenic mouse, a model of the differentcomponents of Alzheimer's disease (Caccamo et al., 2006 Neuron).Finally, the mAChR agonist cevimeline has been shown to give a small,but significant, reduction in cerebrospinal fluid levels of AβinAlzheimer's patients, thus demonstrating potential disease modifyingefficacy (Nitsch et al., 2000 Neurol).

Furthermore, preclinical studies have suggested that mAChR agonistsdisplay an atypical antipsychotic-like profile in a range ofpre-clinical paradigms. The mAChR agonist, xanomeline, reverses a numberof dopamine driven behaviours, including amphetamine induced locomotionin rats, apomorphine induced climbing in mice, dopamine agonist driventurning in unilateral 6-OH-DA lesioned rats and amphetamine inducedmotor unrest in monkeys (without EPS liability). It also has been shownto inhibit A10, but not A9, dopamine cell firing and conditionedavoidance and induces c-fos expression in prefrontal cortex and nucleusaccumbens, but not in striatum in rats. These data are all suggestive ofan atypical antipsychotic-like profile (Mirza et al., 1999 CNS DrugRev).

Xanomeline, sabcomeline, milameline and cevimeline have all progressedinto various stages of clinical development for the treatment ofAlzheimer's disease and/or schizophrenia. Phase II clinical studies withxanomeline demonstrated its efficacy versus various cognitive symptomdomains, including behavioural disturbances and hallucinationsassociated with Alzheimer's disease (Bodick et al., 1997 Arch Neurol).This compound was also assessed in a small Phase II study ofschizophrenics and gave a significant reduction in positive and negativesymptoms when compared to placebo control (Shekhar et al., 2008 Am JPsych). However, in all clinical studies xanomeline and other relatedmAChR agonists have displayed an unacceptable safety margin with respectto cholinergic side effects, including nausea, gastrointestinal pain,diarrhea, diaphoresis (excessive sweating), hypersalivation (excessivesalivation), syncope and bradycardia.

Muscarinic receptors are involved in central and peripheral pain. Paincan be divided into three different types: acute, inflammatory, andneuropathic. Acute pain serves an important protective function inkeeping the organism safe from stimuli that may produce tissue damagehowever management of post-surgical pain is required. Inflammatory painmay occur for many reasons including tissue damage, autoimmune response,and pathogen invasion and is triggered by the action of inflammatorymediators such as neuropeptides and prostaglandins which result inneuronal inflammation and pain. Neuropathic pain is associated withabnormal painful sensations to non-painful stimuli. Neuropathic pain isassociated with a number of different diseases/traumas such as spinalcord injury, multiple sclerosis, diabetes (diabetic neuropathy), viralinfection (such as HIV or Herpes). It is also common in cancer both as aresult of the disease or a side effect of chemotherapy. Activation ofmuscarinic receptors has been shown to be analgesic across a number ofpain states through the activation of receptors in the spinal cord andhigher pain centres in the brain. Increasing endogenous levels ofacetylcholine through acetylcholinesterase inhibitors, direct activationof muscarinic receptors with agonists or allosteric modulators has beenshown to have analgesic activity. In contrast blockade of muscarinicreceptors with antagonists or using knockout mice increases painsensitivity. Evidence for the role of the M1 receptor in pain isreviewed by D. F. Fiorino and M. Garcia-Guzman, 2012.

Recently, a small number of compounds have been identified which displayimproved selectivity for the M₁ mAChR subtype over the peripherallyexpressed mAChR subtypes (Bridges et al., 2008 Bioorg Med Chem Lett;Johnson et al., 2010 Bioorg Med Chem Lett; Budzik et al., 2010 ACS MedChem Lett). Despite increased levels of selectivity versus the M₃ mAChRsubtype, some of these compounds retain significant agonist activity atboth this subtype and the M₂ mAChR subtype. Herein we describe a seriesof compounds which unexpectedly display high levels of selectivity forthe M₁ mAChR over the M₂ and M₃ receptor subtypes.

FIGURES

Compounds of the invention reduce scopolamine-induced amnesia in adose-dependent manner.

FIG. 1 shows that Example 9 Isomer 2 was found to reversescopolamine-induced amnesia of the paradigm in a dose-dependent manner,with an approximate ED50 of ca. 10 mg/kg (po). The effect of 30 mg/kgwas similar to that produced by the cholinesterase inhibitor donepezil(0.1 mg/kg, ip) which served as a positive control.

THE INVENTION

The present invention provides compounds having activity as muscannic M1receptor agonists. More particularly, the invention provides compoundsthat exhibit selectivity for the M1 receptor relative to the M2 and M3receptor subtypes.

Accordingly, in a first embodiment (Embodiment 1.1), the inventionprovides a compound of the formula (1):

or a salt thereof, wherein:

p is 0, 1 or 2;

X¹ and X² are saturated hydrocarbon groups which together contain atotal of five to nine carbon atoms and which link together such that themoiety:

forms a bicyclic ring system;

R¹ is a C₁₋₁₀ non-aromatic hydrocarbon group which is optionallysubstituted with one to six fluorine atoms and wherein one or two, butnot all, carbon atoms of the hydrocarbon group may optionally bereplaced by a heteroatom selected from O, N and S and oxidised formsthereof;

R² is hydrogen or a C₁₋₁₀ non-aromatic hydrocarbon group;

or R¹ and R² together with the nitrogen atom to which they are attachedform a non-aromatic heterocyclic ring of four to nine ring members,wherein the heterocyclic ring may optionally contain a second heteroatomselected from O, N and S and oxidised forms thereof; and wherein theheterocyclic ring may optionally be substituted with one to sixsubstituents selected from C₁₋₂ alkyl; fluorine; and cyano;

R³ is selected from hydrogen; halogen; cyano; hydroxy; C₁₋₃ alkoxy; anda C₁₋₅ non-aromatic hydrocarbon group which is optionally substitutedwith one to six fluorine atoms and wherein one or two, but not all,carbon atoms of the hydrocarbon group may optionally be replaced by aheteroatom selected from O, N and S;

R⁴ is a C₁₋₆ non-aromatic hydrocarbon group which is optionallysubstituted with one to six fluorine atoms and wherein one or two, butnot all, carbon atoms of the hydrocarbon group may optionally bereplaced by a heteroatom selected from O, N and S and oxidised formsthereof; and

R⁵ is fluorine.

Particular and preferred compounds of the formula (1) are as defined inthe following Embodiments 1.2 to 1.64:

1.2 A compound according to Embodiment 1.1 wherein R¹ is a C₁₋₁₀non-aromatic hydrocarbon group containing 0, 1 or 2 carbon-carbonmultiple bonds, wherein the hydrocarbon group is optionally substitutedwith one to six fluorine atoms and wherein one or two, but not all,carbon atoms of the hydrocarbon group may optionally be replaced by aheteroatom selected from O, N and S and oxidised forms thereof.

1.3 A compound according to either of Embodiments 1.1 and 1.2 wherein R¹is selected from C₁₋₆ alkyl; C₂₋₆ alkenyl; C₂₋₆ alkynyl; and C₁₋₁₀non-aromatic hydrocarbon groups consisting of or containing a C₃₋₁₀cycloalkyl or C₅₋₆ cycloalkenyl group; each of the said alkyl, alkenyl,alkynyl and non-aromatic hydrocarbon groups being optionally substitutedwith one to six fluorine atoms and wherein one or two, but not all,carbon atoms of each of the alkyl, alkenyl, alkynyl and non-aromatichydrocarbon groups may optionally be replaced by a heteroatom selectedfrom O, N and S and oxidised forms thereof.

1.4 A compound according to any one of Embodiments 1.1 to 1.3 wherein R¹is selected from:

-   -   C₁₋₆ alkyl optionally substituted with 1 to 6 fluorine atoms;    -   methoxy-C₁₋₄ alkyl optionally substituted with 1 to 6 fluorine        atoms;    -   C₁₋₆ alkoxy;    -   C₂₋₆ alkenyl;    -   C₂₋₆ alkynyl;    -   C₃₋₆ cycloalkyl optionally substituted with one or two methyl        groups;    -   C₄₋₅ cycloalkyl-CH₂— wherein the C₄₋₅ cycloalkyl moiety is        optionally substituted with one C₁₋₂ alkyl group and wherein one        carbon atom of the C₄₋₅ cycloalkyl moiety may optionally be        replaced by an oxygen atom;    -   cyclopropyl-C₁₋₃ alkyl;    -   cyclopentenyl; and    -   methyl-bicyclo[2.2.2]octanyl.

1.5 A compound according to Embodiment 1.4 wherein R¹ is selected from:

-   -   C₁₋₅ alkyl optionally substituted with 1 to 6 fluorine atoms;    -   C₃₋₆ cycloalkyl optionally substituted with one or two methyl        groups;    -   C₄₋₅ cycloalkyl-CH₂— wherein the C₄₋₅ cycloalkyl moiety is        optionally substituted with one C₁₋₂ alkyl group and wherein one        carbon atom of the C₄₋₅ cycloalkyl moiety may optionally be        replaced by an oxygen atom;    -   cyclopropyl-C₁₋₃ alkyl; and    -   methyl-bicyclo[2.2.2]octanyl.

1.6 A compound according to Embodiment 1.5 wherein R¹ is C₁₋₅ alkyloptionally substituted with 1 to 6 fluorine atoms.

1.7 A compound according to Embodiment 1.5 wherein R¹ is C₃₋₆ cycloalkyloptionally substituted with one or two methyl groups.

1.8 A compound according to Embodiment 1.5 wherein R¹ is C₄₋₅cycloalkyl-CH₂— wherein the C₄₋₅ cycloalkyl moiety is optionallysubstituted with one C₁₋₂ alkyl group and wherein one carbon atom of theC₄₋₅ cycloalkyl moiety may optionally be replaced by an oxygen atom.

1.9 A compound according to Embodiment 1.5 wherein R¹ iscyclopropyl-C₁₋₃ alkyl.

1.10 A compound according to Embodiment 1.5 wherein R¹ ismethyl-bicyclo[2.2.2]octanyl.

1.11 A compound according to Embodiment 1.4 wherein R¹ is selected fromgroups A to AH below:

where the asterisk denotes the point of attachment of the group to theamide nitrogen atom.

1.12 A compound according to Embodiment 1.11 wherein R¹ is selected fromgroups A, B, D, E, F, G, L, M, N, O, Q, R, T, V, W, Y, AB, AE, AF, AGand AH.

1.13 A compound according to any one of Embodiments 1.1 to 1.4 whereinR¹ is selected from 2-methylpropyl; 2,2-dimethylpropyl; tert-butyl;2-methyl-but-2-yl; 2,3-dimethylbut-2-yl; cyclopropylmethyl;cyclobutylmethyl; cyclopentyl; cyclopentylmethyl; 1-methylcyclobutyl;1-methylcyclopentyl; 1-methylcyclohexyl; 1-methylcyclopentylmethyl;cyclopropyl-prop-2-yl; 1-methylcyclobutylmethyl,1-ethyl-cyclobutylmethyl, 1-(fluoromethyl)cyclobutyl,1-(1,1,1-trideuteromethyl) cyclobutyl and1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl groups.

1.14 A compound according to Embodiment 1.13 wherein R¹ is selected from2-methylpropyl and 1-methylcyclobutyl.

1.15 A compound according to Embodiment 1.14 wherein R¹ is2-methylpropyl.

1.16 A compound according to Embodiment 1.14 wherein R¹ is1-methylcyclobutyl.

1.17 A compound according to any one of Embodiments 1.1 to 1.16 whereinR² is selected from hydrogen and C₁₋₆ alkyl.

1.18 A compound according to Embodiment 1.17 wherein R² is selected fromhydrogen, methyl, ethyl and isopropyl.

1.19 A compound according to Embodiment 1.18 wherein R² is hydrogen.

1.20 A compound according to any one of Embodiments 1.1 to 1.19 whereinR³ is selected from hydrogen, halogen, cyano, hydroxy, C₁₋₃ alkoxy andC₁₋₄ alkyl.

1.21 A compound according to Embodiment 1.20 wherein R³ is selected fromhydrogen, fluorine, methyl and methoxy.

1.22 A compound according to Embodiment 1.21 wherein R³ is selected fromhydrogen, fluorine and methoxy.

1.23 A compound according to Embodiment 1.22 wherein R³ is selected fromhydrogen and fluorine.

1.24 A compound according to Embodiment 1.23 wherein R³ is hydrogen.

1.25 A compound according to Embodiment 1.23 wherein R³ is fluorine.

1.26 A compound according to any one of Embodiments 1.1 to 1.25 whereinR⁴ is an acyclic C₁₋₆ hydrocarbon group.

1.27 A compound according to Embodiment 1.26 wherein R⁴ is an acyclicC₁₋₃ hydrocarbon group.

1.28 A compound according to Embodiment 1.27 wherein R⁴ is a C₁₋₃ alkylgroup or a C₂₋₃ alkynyl group.

1.29 A compound according to Embodiment 1.28 wherein R¹ is selected frommethyl, ethyl, ethynyl and 1-propynyl.

1.30 A compound according to Embodiment 1.29 wherein R¹ is methyl.

1.31 A compound according to any one of Embodiments 1.1 to 1.30 whereinp is 0 or 1.

1.32 A compound according to Embodiment 1.31 wherein p is 0.

1.33 A compound according to Embodiment 1.31 wherein p is 1.

1.34 A compound according to any one of Embodiments 1.1 to 1.33 whereinX¹ and X² together contain six or seven carbon atoms.

1.35 A compound according to any one of Embodiments 1.1 to 1.34 whereinthe bicyclic ring system formed by the moiety:

is a bridged bicyclic ring system.

1.36 A compound according to Embodiment 1.35 wherein the bridgedbicyclic ring system is an azabicyclo-octane or azabicyclo-nonane ringsystem.

1.37 A compound according to Embodiment 1.36 wherein the bridgedbicyclic ring system is selected from an 8-aza-bicyclo[3.2.1]octane ringsystem, a 9-aza-bicyclo[3.3.1]nonane ring system and a6-aza-bicyclo[3.2.1]octane ring system.

1.38 A compound according to Embodiment 1.37 wherein the bridgedbicyclic ring system is selected from ring systems BA, BB and BC below:

1.39 A compound according to Embodiment 1.38 wherein the bridgedbicyclic ring system is ring system BA.

1.40 A compound according to Embodiment 1.38 wherein the bridgedbicyclic ring system is ring system BB.

1.41 A compound according to Embodiment 1.38 wherein the bridgedbicyclic ring system is ring system BC.

1.42 A compound according to any one of Embodiments 1.1 to 1.34 whereinthe bicyclic ring system formed by the moiety:

is a spirocyclic ring system.

1.43 A compound according to Embodiment 1.42 wherein the spirocyclicring system is a 2-aza-spiro[3.4]octane or a 6-aza-spiro[3.4]octane ringsystem.

1.44 A compound according to Embodiment 1.43 wherein the spirocyclicring system is selected from ring systems CA and CB below:

1.45 A compound according to Embodiment 1.44 wherein the spirocyclicring system is ring system CA.

1.46 A compound according to Embodiment 1.44 wherein the spirocyclicring system is ring system CB.

1.47 A compound according to any one of Embodiments 1.1 to 1.34 whereinthe bicyclic ring system formed by the moiety:

is a fused bicyclic ring system.

1.48 A compound according to Embodiment 1.47 wherein the fused bicyclicring system is a cyclopentanopyrrolidine ring system.

1.49 A compound according to Embodiment 1.47 wherein thecyclopentanopyrrolidine ring system has structure DA below

1.50 A compound according to any one of Embodiments 1.1 to 1.34 whereinthe bicyclic ring system formed by the moiety:

is selected from:

(a) an azabicyclo-octane or azabicyclo-nonane ring system;

(b) a 2-aza-spiro[3.4]octane or a 6-aza-spiro[3.4]octane ring system;and

(c) a cyclopentanopyrrolidine ring system.

1.51 A compound according to Embodiment 1.50 wherein the bicyclic ringsystem formed by the moiety:

is selected from ring systems BA, BB, BC, CA, CB and DA below:

1.52 A compound according to Embodiment 1.1 having the formula (2):

wherein R¹, R³, R⁴, R⁵ and p are as defined in any one of Embodiments1.1 to 1.34; q is 1, 2 or 3 and r is 0 or 1, provided that the total ofq and r is 2 or 3.

1.53 A compound according to Embodiment 1.52 wherein (i) r is 0 and q is2; (ii) r is 0 and q is 3; or (iii) r is 1 and q is 1.

1.54 A compound according to Embodiment 1.1 having the formula (3):

wherein R¹, R³, R⁴, R⁵ and p are as defined in any one of Embodiments1.1 to 1.34; s is 0 or 1 and t is 0 or 1.

1.55. A compound according to Embodiment 1.54 wherein the total of s andt is 1.

1.56 A compound according to Embodiment 1.55 wherein s is 0 and t is 1.

1.57 A compound according to Embodiment 1.55 wherein s is 1 and t is 0.

1.58 A compound according to Embodiment 1.1 having the formula (4):

wherein R¹, R³, R⁴, R⁵ and p are as defined in any one of Embodiments1.1 to 1.34; and u, v, w and x are each 0, 1 or 2 provided that thetotal u+v+w+x is at least 1 and does not exceed 5.

1.59 A compound according to Embodiment 1.58 wherein each of u, v, w andx is 1.

1.60 A compound according to Embodiment 1.1 which is as defined in anyone of Examples 1 to 13.

1.61 A compound according to any one of Embodiments 1.1 to 1.60 having amolecular weight of less than 550, for example less than 500, or lessthan 450.

1.62 A compound according to any one of Embodiments 1.1 to 1.61 which isin the form of a salt.

1.63 A compound according to Embodiment 1.62 wherein the salt is an acidaddition salt.

1.64 A compound according to Embodiment 1.62 or Embodiment 1.63 whereinthe salt is a pharmaceutically acceptable salt.

Definitions

In this application, the following definitions apply, unless indicatedotherwise.

The term “treatment”, in relation to the uses of the compounds of theformula (1), is used to describe any form of intervention where acompound is administered to a subject suffering from, or at risk ofsuffering from, or potentially at risk of suffering from the disease ordisorder in question. Thus, the term “treatment” covers bothpreventative (prophylactic) treatment and treatment where measurable ordetectable symptoms of the disease or disorder are being displayed.

The term “effective therapeutic amount” as used herein (for example inrelation to methods of treatment of a disease or condition) refers to anamount of the compound which is effective to produce a desiredtherapeutic effect. For example, if the condition is pain, then theeffective therapeutic amount is an amount sufficient to provide adesired level of pain relief. The desired level of pain relief may be,for example, complete removal of the pain or a reduction in the severityof the pain.

In formula (1), X¹ and X² are saturated hydrocarbon groups whichtogether contain a total of five to nine carbon atoms and which linktogether such that the moiety:

forms a bicyclic ring system. The term “bicyclic ring system” as usedherein in the context of X¹ and X² includes fused bicyclic systems,bridged bicyclic systems and spirocyclic systems containing two linkedrings.

The term “non-aromatic hydrocarbon group” (as in “C₁₋₁₀ non-aromatichydrocarbon group” or “acyclic C₁₋₅ non-aromatic hydrocarbon group”refers to a group consisting of carbon and hydrogen atoms and whichcontains no aromatic rings. The hydrocarbon group may be fully saturatedor may contain one or more carbon-carbon double bonds or carbon-carbontriple bonds, or mixtures of double and triple bonds. The hydrocarbongroup may be a straight chain or branched chain group or may consist ofor contain a cyclic group. Thus the term non-aromatic hydrocarbonincludes alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl,cycloalkylalkyl, cycloalkenyl alkyl and so on.

The terms “alkyl”, “alkenyl”, “alkynyl”, “cycloalkyl” and “cycloalkenyl”are used in their conventional sense (e.g. as defined in the IUPAC GoldBook) unless indicated otherwise.

The term “cycloalkyl” as used herein, where the specified number ofcarbon atoms permits, includes both monocyclic cycloalkyl groups such ascyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl, andbicyclic and tricyclic groups. Bicyclic cycloalkyl groups includebridged ring systems such as bicycloheptane, bicyclooctane andadamantane.

In the definitions of R¹, R³ and R⁴ above, where stated, one or two butnot all, carbon atoms of the non-aromatic hydrocarbon group mayoptionally be replaced by a heteroatom selected from O, N and S and (inthe case of R¹ and R⁴) oxidised forms thereof. In the definition of themoiety R^(b) forming part of R⁶, one or two, but not all, carbon atomsof the hydrocarbon group may optionally be replaced by a heteroatomselected from O, N and S or by a group selected from CO, X¹C(X²),C(X²)X¹, SO and SO₂. It will be appreciated that when a carbon atom isreplaced by a heteroatom, the lower valencies of the heteroatomscompared to carbon means that fewer atoms will be bonded to theheteroatoms than would have been bonded to the carbon atom that has beenreplaced. Thus, for example, replacement of of a carbon atom (valency offour) in a CH₂ group by oxygen (valency of two) will mean that theresulting molecule will contain two less hydrogen atoms and replacementof a carbon atom (valency of four) in a CH₂ group by nitrogen (valencyof three) will mean that the resulting molecule will contain one lesshydrogen atom.

Examples of a heteroatom replacements for carbon atoms includereplacement of a carbon atom in a —CH₂—CH₂—CH₂— chain with oxygen orsulfur to give an ether —CH₂—O—CH₂— or thioether —CH₂—S—CH₂—,replacement of a carbon atom in a group CH₂—C≡C—H with nitrogen to givea nitrile (cyano) group CH₂—C≡N, replacement of a carbon atom in a group—CH₂—CH₂—CH₂— with C═O to give a ketone —CH₂—C(O)—CH₂—, replacement of acarbon atom in a group —CH₂—CH₂—CH₂— with S═O or SO₂ to give a sulfoxide—CH₂—S(O)—CH₂— or sulfone —CH₂—S(O)₂—CH₂—, replacement of a carbon atomin a —CH₂—CH₂—CH₂— chain with C(O)NH to give an amide —CH₂—CH₂—C(O)—NH—,replacement of a carbon atom in a —CH₂—CH₂—CH₂— chain with nitrogen togive an amine —CH₂—NH—CH₂—, and replacement of a carbon atom in a—CH₂—CH₂—CH₂— chain with C(O)O to give an ester (or carboxylic acid)—CH₂—CH₂—C(O)—O—. In each such replacement, at least one carbon atom ofthe hydrocarbon group must remain.

Salts

Many compounds of the formula (1) can exist in the form of salts, forexample acid addition salts or, in certain cases salts of organic andinorganic bases such as carboxylate, sulfonate and phosphate salts. Allsuch salts are within the scope of this invention, and references tocompounds of the formula (1) include the salt forms of the compounds asdefined in Embodiments 1.62 to 1.64.

The salts are typically acid addition salts.

The salts of the present invention can be synthesized from the parentcompound that contains a basic or acidic moiety by conventional chemicalmethods such as methods described in Pharmaceutical Salts: Properties,Selection, and Use, P. Heinrich Stahl (Editor), Camille G. Wermuth(Editor), ISBN: 3-90639-026-8, Hardcover, 388 pages, August 2002.Generally, such salts can be prepared by reacting the free acid or baseforms of these compounds with the appropriate base or acid in water orin an organic solvent, or in a mixture of the two; generally, nonaqueousmedia such as ether, ethyl acetate, ethanol, isopropanol, oracetonitrile are used.

Acid addition salts (as defined in Embodiment 1.63) may be formed with awide variety of acids, both inorganic and organic. Examples of acidaddition salts falling within Embodiment 1.63 include mono- or di-saltsformed with an acid selected from the group consisting of acetic,2,2-dichloroacetic, adipic, alginic, ascorbic (e.g. L-ascorbic),L-aspartic, benzenesulfonic, benzoic, 4-acetamidobenzoic, butanoic, (+)camphoric, camphor-sulfonic, (+)-(1 S)-camphor-10-sulfonic, capric,caproic, caprylic, cinnamic, citric, cyclamic, dodecylsulfuric,ethane-1,2-disulfonic, ethanesulfonic, 2-hydroxyethanesulfonic, formic,fumaric, galactaric, gentisic, glucoheptonic, D-gluconic, glucuronic(e.g. D-glucuronic), glutamic (e.g. L-glutamic), α-oxoglutaric,glycolic, hippuric, hydrohalic acids (e.g. hydrobromic, hydrochloric,hydriodic), isethionic, lactic (e.g. (+)-L-lactic, (±)-DL-lactic),lactobionic, maleic, malic, (−)-L-malic, malonic, (±)-DL-mandelic,methanesulfonic, naphthalene-2-sulfonic, naphthalene-1,5-disulfonic,1-hydroxy-2-naphthoic, nicotinic, nitric, oleic, orotic, oxalic,palmitic, pamoic, phosphoric, propionic, pyruvic. L-pyroglutamic,salicylic, 4-amino-salicylic, sebacic, stearic, succinic, sulfuric,tannic, (+)-L-tartaric, thiocyanic, p-toluenesulfonic, undecylenic andvaleric acids, as well as acylated amino acids and cation exchangeresins.

Where the compounds of the formula (1) contain an amine function, thesemay form quaternary ammonium salts, for example by reaction with analkylating agent according to methods well known to the skilled person.Such quaternary ammonium compounds are within the scope of formula (1).

The compounds of the invention may exist as mono- or di-salts dependingupon the pKa of the acid from which the salt is formed.

The salt forms of the compounds of the invention are typicallypharmaceutically acceptable salts, and examples of pharmaceuticallyacceptable salts are discussed in Berge et al., 1977, “PharmaceuticallyAcceptable Salts,” J. Pharm. Sci., Vol. 66, pp. 1-19. However, saltsthat are not pharmaceutically acceptable may also be prepared asintermediate forms which may then be converted into pharmaceuticallyacceptable salts. Such non-pharmaceutically acceptable salts forms,which may be useful, for example, in the purification or separation ofthe compounds of the invention, also form part of the invention.

Stereoisomers

Stereoisomers are isomeric molecules that have the same molecularformula and sequence of bonded atoms but which differ only in thethree-dimensional orientations of their atoms in space. Thestereoisomers can be, for example, geometric isomers or optical isomers.

Geometric Isomers

With geometric isomers, the isomerism is due to the differentorientations of an atom or group about a double bond, as in cis andtrans (Z and E) isomerism about a carbon-carbon double bond, or cis andtrans isomers about an amide bond, or syn and anti isomerism about acarbon nitrogen double bond (e.g. in an oxime), or rotational isomerismabout a bond where there is restricted rotation, or cis and transisomerism about a ring such as a cycloalkane ring.

Accordingly, in another embodiment (Embodiment 1.65), the inventionprovides a geometric isomer of a compound according to any one ofEmbodiments 1.1 to 1.64.

Optical Isomers

Where compounds of the formula contain one or more chiral centres, andcan exist in the form of two or more optical isomers, references to thecompounds include all optical isomeric forms thereof (e.g. enantiomers,epimers and diastereoisomers), either as individual optical isomers, ormixtures (e.g. racemic mixtures) or two or more optical isomers, unlessthe context requires otherwise.

Accordingly, in another embodiment (Embodiment 1.66) the inventionprovides a compound according to any one of Embodiments 1.1 to 1.65which contains a chiral center.

The optical isomers may be characterised and identified by their opticalactivity (i.e. as + and − isomers, or d and l isomers) or they may becharacterised in terms of their absolute stereochemistry using the “Rand S” nomenclature developed by Cahn, Ingold and Prelog, see AdvancedOrganic Chemistry by Jerry March, 4^(th) Edition, John Wiley & Sons, NewYork, 1992, pages 109-114, and see also Cahn, Ingold & Prelog, Angew.Chem. Int. Ed. Engl., 1966, 5, 385-415 Optical isomers can be separatedby a number of techniques including chiral chromatography(chromatography on a chiral support) and such techniques are well knownto the person skilled in the art. As an alternative to chiralchromatography, optical isomers can be separated by formingdiastereoisomeric salts with chiral acids such as (+)-tartaric acid,(−)-pyroglutamic acid, (−)-di-toluoyl-L-tartaric acid, (+)-mandelicacid, (−)-malic acid, and (−)-camphorsulphonic, separating thediastereoisomers by preferential crystallisation, and then dissociatingthe salts to give the individual enantiomer of the free base.

Where compounds of the invention exist as two or more optical isomericforms, one enantiomer in a pair of enantiomers may exhibit advantagesover the other enantiomer, for example, in terms of biological activity.Thus, in certain circumstances, it may be desirable to use as atherapeutic agent only one of a pair of enantiomers, or only one of aplurality of diastereoisomers.

Accordingly, in another embodiment (Embodiment 1.67), the inventionprovides compositions containing a compound according to Embodiment 1.66having one or more chiral centres, wherein at least 55% (e.g. at least60%, 65%, 70%, 75%, 80%, 85%, 90% or 95%) of the compound of Embodiment1.65 is present as a single optical isomer (e.g. enantiomer ordiastereoisomer).

In one general embodiment (Embodiment 1.68), 99% or more (e.g.substantially all) of the total amount of the compound (or compound foruse) of Embodiment 1.66 is present as a single optical isomer.

For example, in one embodiment (Embodiment 1.69 the compound is presentas a single enantiomer.

In another embodiment (Embodiment 1.70), the compound is present as asingle diastereoisomer.

The invention also provides mixtures of optical isomers, which may beracemic or non-racemic. Thus, the invention provides:

1.71 A compound according to Embodiment 1.66 which is in the form of aracemic mixture of optical isomers.

1.72 A compound according to Embodiment 1.66 which is in the form of anon-racemic mixture of optical isomers.

Isotopes

The compounds of the invention as defined in any one of Embodiments 1.1to 1.72 may contain one or more isotopic substitutions, and a referenceto a particular element includes within its scope all isotopes of theelement. For example, a reference to hydrogen includes within its scope¹H, ²H (D), and ³H (T). Similarly, references to carbon and oxygeninclude within their scope respectively ¹²C, ¹³C and ¹⁴C and ¹⁶O and¹⁸O.

In an analogous manner, a reference to a particular functional groupalso includes within its scope isotopic variations, unless the contextindicates otherwise. For example, a reference to an alkyl group such asan ethyl group also covers variations in which one or more of thehydrogen atoms in the group is in the form of a deuterium or tritiumisotope, e.g. as in an ethyl group in which all five hydrogen atoms arein the deuterium isotopic form (a perdeuteroethyl group).

The isotopes may be radioactive or non-radioactive. In one embodiment ofthe invention (Embodiment 1.73), the compound of any one of Embodiments1.1 to 1.72 contains no radioactive isotopes. Such compounds arepreferred for therapeutic use.

In another embodiment (Embodiment 1.74), however, the compound of anyone of Embodiments 1.1 to 1.72 may contain one or more radioisotopes.Compounds containing such radioisotopes may be useful in a diagnosticcontext.

Solvates

Compounds of the formula (1) as defined in any one of Embodiments 1.1 to1.74 may form solvates. Preferred solvates are solvates formed by theincorporation into the solid state structure (e.g. crystal structure) ofthe compounds of the invention of molecules of a non-toxicpharmaceutically acceptable solvent (referred to below as the solvatingsolvent). Examples of such solvents include water, alcohols (such asethanol, isopropanol and butanol) and dimethylsulphoxide. Solvates canbe prepared by recrystallising the compounds of the invention with asolvent or mixture of solvents containing the solvating solvent. Whetheror not a solvate has been formed in any given instance can be determinedby subjecting crystals of the compound to analysis using well known andstandard techniques such as thermogravimetric analysis (TGE),differential scanning calorimetry (DSC) and X-ray crystallography. Thesolvates can be stoichiometric or non-stoichiometric solvates.Particularly preferred solvates are hydrates, and examples of hydratesinclude hemihydrates, monohydrates and dihydrates.

Accordingly, in further embodiments 1.75 and 1.76, the inventionprovides:

1.75 A compound according to any one of Embodiments 1.1 to 1.74 in theform of a solvate.

1.76 A compound according to Embodiment 1.75 wherein the solvate is ahydrate.

For a more detailed discussion of solvates and the methods used to makeand characterise them, see Bryn et al., Solid-State Chemistry of Drugs,Second Edition, published by SSCI, Inc of West Lafayette, Ind., USA,1999, ISBN 0-967-06710-3.

Alternatively, rather than existing as a hydrate, the compound of theinvention may be anhydrous. Therefore, in another embodiment (Embodiment1.77), the invention provides a compound as defined in any one ofEmbodiments 1.1 to 1.74 in an anhydrous form (e.g. anhydrous crystallineform).

Crystalline and Amorphous Forms

The compounds of any one of Embodiments 1.1 to 1.77 may exist in acrystalline or non-crystalline (e.g. amorphous) state. Whether or not acompound exists in a crystalline state can readily be determined bystandard techniques such as X-ray powder diffraction (XRPD). Crystalsand their crystal structures can be characterised using a number oftechniques including single crystal X-ray crystallography, X-ray powderdiffraction (XRPD), differential scanning calorimetry (DSC) and infrared spectroscopy, e.g. Fourier Transform infra-red spectroscopy (FTIR).The behaviour of the crystals under conditions of varying humidity canbe analysed by gravimetric vapour sorption studies and also by XRPD.Determination of the crystal structure of a compound can be performed byX-ray crystallography which can be carried out according to conventionalmethods such as those described herein and as described in Fundamentalsof Crystallography, C. Giacovazzo, H. L. Monaco, D. Viterbo, F.Scordari. G. Gilli, G. Zanotti and M. Catti, (International Union ofCrystallography/Oxford University Press, 1992 ISBN 0-19-855578-4 (p/b),0-19-85579-2 (h/b)). This technique involves the analysis andinterpretation of the X-ray diffraction of single crystal. In anamorphous solid, the three dimensional structure that normally exists ina crystalline form does not exist and the positions of the moleculesrelative to one another in the amorphous form are essentially random,see for example Hancock et al. J. Pharm. Sci. (1997), 86, 1).

Accordingly, in further embodiments, the invention provides:

1.78 A compound according to any one of Embodiments 1.1 to 1.77 in acrystalline form.

1.79 A compound according to any one of Embodiments 1.1 to 1.77 whichis:

(a) from 50% to 100% crystalline, and more particularly is at least 50%crystalline, or at least 60% crystalline, or at least 70% crystalline,or at least 80% crystalline, or at least 90% crystalline, or at least95% crystalline, or at least 98% crystalline, or at least 99%crystalline, or at least 99.5% crystalline, or at least 99.9%crystalline, for example 100% crystalline.

1.80 A compound according to any one of Embodiments 1.1 to 1.77 which isin an amorphous form.

Prodrugs

The compounds of the formula (1) as defined in any one of Embodiments1.1 to 1.74 may be presented in the form of a pro-drug. By “prodrugs” ismeant for example any compound that is converted in vivo into abiologically active compound of the formula (1), as defined in any oneof Embodiments 1.1 to 1.74.

For example, some prodrugs are esters of the active compound (e.g., aphysiologically acceptable metabolically labile ester). Duringmetabolism, the ester group (—C(═O)OR) is cleaved to yield the activedrug. Such esters may be formed by esterification, for example, of anyhydroxyl groups present in the parent compound with, where appropriate,prior protection of any other reactive groups present in the parentcompound, followed by deprotection if required.

Also, some prodrugs are activated enzymatically to yield the activecompound, or a compound which, upon further chemical reaction, yieldsthe active compound (for example, as in ADEPT, GDEPT, LIDEPT, etc.). Forexample, the prodrug may be a sugar derivative or other glycosideconjugate, or may be an amino acid ester derivative.

Accordingly, in another embodiment (Embodiment 1.81), the inventionprovides a pro-drug of a compound as defined in any one of Embodiments1.1 to 1.74 wherein the compound contains a functional group which isconvertable under physiological conditions to form a hydroxyl group oramino group.

Complexes and Clathrates

Also encompassed by formula (1) in Embodiments 1.1 to 1.81 are complexes(e.g. inclusion complexes or clathrates with compounds such ascyclodextrins, or complexes with metals) of the compounds of Embodiments1.1 to 1.81.

Accordingly, in another embodiment (Embodiment 1.82), the inventionprovides a compound according to any one of Embodiments 1.1 to 1.81 inthe form of a complex or clathrate.

Biological Activity and Therapeutic Uses

The compounds of the present invention have activity as muscarinic M1receptor agonists. The muscarinic activity of the compounds can bedetermined using the Phospho-ERK1/2 assay described in Example A below.

A significant advantage of compounds of the invention is that they arehighly selective for the M1 receptor relative to the M2 and M3 receptorsubtypes. Compounds of the invention are neither agonists norantagonists of the M2 and M3 receptor subtypes. For example, whereascompounds of the invention typically have pEC₅₀ values of at least 6(preferably at least 6.5) and E_(max) values of greater than 80(preferably greater than 95) against the M1 receptor in the functionalassay described in Example A, they may have pEC₅₀ values of less than 5and E_(max) values of less than 20% when tested against the M2 and M3subtypes in the functional assay of Example A.

Accordingly, in Embodiments 2.1 to 2.9, the invention provides:

2.1 A compound according to any one of Embodiments 1.1 to 1.82 for usein medicine.

2.2 A compound according to any one of Embodiments 1.1 to 1.82 for useas a muscarinic M1 receptor agonist.

2.3 A compound according to any one of Embodiments 1.1 to 1.82 which isa muscarinic M1 receptor agonist having a pEC₅₀ in the range from 6.0 to7.9 and an E_(max) of at least 90 against the M1 receptor in the assayof Example A herein or an assay substantially similar thereto.

2.4 A compound according to Embodiment 2.3 which is a muscarinic M1receptor agonist having a pEC₅₀ in the range from 6.5 to 7.5.

2.5 A compound according to Embodiment 2.3 or Embodiment 2.4 having anE_(max) of at least 95 against the M1 receptor.

2.6 A compound according to any one of Embodiments 2.3 to 2.5 which isselective for the M1 receptor compared to the muscarinic M2 and M3receptors.

2.7 A compound according to any one of Embodiments 2.3 to 2.6 which hasa pEC₅₀ of less than 5 and an E_(max) of less than 50 against themuscarinic M2 and M3 receptor subtypes.

2.8 A compound according to Embodiment 2.7 which has a pEC₅₀ of lessthan 4.5 and/or an E_(max) of less than 30 against the muscarinic M2 andM3 receptor subtypes.

2.9 A compound according to any one of Embodiments 1.1 to 1.82 andEmbodiments 2.3 to 2.8 for use in the treatment of a disease orcondition mediated by the muscarinic M1 receptor.

By virtue of their muscarinic M1 receptor agonist activity, compounds ofthe invention can be used in the treatment of Alzheimer's disease,schizophrenia and other psychotic disorders, cognitive disorders andother diseases mediated by the muscarinic M1 receptor, and can also beused in the treatment of various types of pain.

Accordingly, in Embodiments 2.10 to 2.26, the invention provides:

2.10 A compound according to any one of Embodiments 1.1 to 1.82 for usein the treatment of a cognitive disorder or psychotic disorder.

2.11 A compound for use in according to Embodiment 2.10 wherein thecognitive disorder or psychotic disorder comprises, arises from or isassociated with a condition selected from cognitive impairment, MildCognitive Impairment, frontotemporal dementia, vascular dementia,dementia with Lewy bodies, presenile dementia, senile dementia,Friederich's ataxia, Down's syndrome, Huntington's chorea, hyperkinesia,mania, Tourette's syndrome, Alzheimer's disease, progressivesupranuclear palsy, impairment of cognitive functions includingattention, orientation, learning disorders, memory (i.e. memorydisorders, amnesia, amnesic disorders, transient global amnesia syndromeand age-associated memory impairment) and language function; cognitiveimpairment as a result of stroke, Huntington's disease, Pick disease,Aids-related dementia or other dementia states such as Multiinfarctdementia, alcoholic dementia, hypotiroidism-related dementia, anddementia associated to other degenerative disorders such as cerebellaratrophy and amyotropic lateral sclerosis; other acute or sub-acuteconditions that may cause cognitive decline such as delirium ordepression (pseudodementia states) trauma, head trauma, age relatedcognitive decline, stroke, neurodegeneration, drug-induced states,neurotoxic agents, age related cognitive impairment, autism relatedcognitive impairment, Down's syndrome, cognitive deficit related topsychosis, and post-electroconvulsive treatment related cognitivedisorders; cognitive disorders due to drug abuse or drug withdrawalincluding nicotine, cannabis, amphetamine, cocaine, Attention DeficitHyperactivity Disorder (ADHD) and dyskinetic disorders such asParkinson's disease, neuroleptic-induced parkinsonism, and tardivedyskinesias, schizophrenia, schizophreniform diseases, psychoticdepression, mania, acute mania, paranoid, hallucinogenic and delusionaldisorders, personality disorders, obsessive compulsive disorders,schizotypal disorders, delusional disorders, psychosis due tomalignancy, metabolic disorder, endocrine disease or narcolepsy,psychosis due to drug abuse or drug withdrawal, bipolar disorders andand schizo-affective disorder.

2.12 A compound according to any one of Embodiments 1.1 to 1.82 for usein the treatment of Alzheimer's disease.

2.13 A compound according to any one of Embodiments 1.1 to 1.82 for usein the treatment of Schizophrenia.

2.14 A method of treatment of a cognitive disorder in a subject (e.g. amammalian patient such as a human, e.g. a human in need of suchtreatment), which method comprises the administration of atherapeutically effective dose of a compound according to any one ofEmbodiments 1.1 to 1.82.

2.15 A method according to Embodiment 2.14 wherein the cognitivedisorder comprises, arises from or is associated with a condition asdefined in Embodiment 2.11.

2.16 A method according to Embodiment 2.15 wherein the cognitivedisorder arises from or is associated with Alzheimer's disease.

2.17 A method according to Embodiment 2.16 wherein the cognitivedisorder is Schizophrenia.

2.18 The use of a compound according to any one of Embodiments 1.1 to1.82 for the manufacture of a medicament for the treatment of acognitive disorder.

2.19 The use according to Embodiment 2.10 wherein the cognitive disordercomprises, arises from or is associated with a condition as defined inEmbodiment 2.11.

2.20 The use according to Embodiment 2.19 wherein the cognitive disorderarises from or is associated with Alzheimer's disease.

2.21 The use according to Embodiment 2.19 wherein the cognitive disorderis Schizophrenia.

2.22 A compound according to any one of Embodiments 1.1 to 1.82 for thetreatment or lessening the severity of acute, chronic, neuropathic, orinflammatory pain, arthritis, migraine, duster headaches, trigeminalneuralgia, herpetic neuralgia, general neuralgias, visceral pain,osteoarthritis pain, postherpetic neuralgia, diabetic neuropathy,radicular pain, sciatica, back pain, head or neck pain, severe orintractable pain, nociceptive pain, breakthrough pain, postsurgicalpain, or cancer pain.

2.23 A method of treatment or lessening the seventy of acute, chronic,neuropathic, or inflammatory pain, arthritis, migraine, clusterheadaches, trigeminal neuralgia, herpetic neuralgia, general neuralgias,visceral pain, osteoarthritis pain, postherpetic neuralgia, diabeticneuropathy, radicular pain, sciatica, back pain, head or neck pain,severe or intractable pain, nociceptive pain, breakthrough pain,postsurgical pain, or cancer pain, which method comprises theadministration of a therapeutically effective dose of a compoundaccording to any one of Embodiments 1.1 to 1.82.

2.24 A compound according to any one of Embodiments 1.1 to 1.82 for thetreatment of peripheral disorders such as reduction of intra ocularpressure in Glaucoma and treatment of dry eyes and dry mouth includingSjogren's Syndrome.

2.25 A method of treatment of peripheral disorders such as reduction ofintra ocular pressure in Glaucoma and treatment of dry eyes and drymouth including Sjogren's Syndrome, which method comprises theadministration of a therapeutically effective dose of a compoundaccording to any one of Embodiments 1.1 to 1.82.

2.26 The use of a compound according to any one of Embodiments 1.1 to1.82 for the manufacture of a medicament for the treatment or lesseningthe severity of acute, chronic, neuropathic, or inflammatory pain,arthritis, migraine, cluster headaches, trigeminal neuralgia, herpeticneuralgia, general neuralgias, visceral pain, osteoarthritis pain,postherpetic neuralgia, diabetic neuropathy, radicular pain, sciatica,back pain, head or neck pain, severe or intractable pain, nociceptivepain, breakthrough pain, postsurgical pain, or cancer pain or for thetreatment of peripheral disorders such as reduction of intra ocularpressure in Glaucoma and treatment of dry eyes and dry mouth includingSjogren's Syndrome.

2.27 The use of a compound according to any one of Embodiments 1.1 to1.82 for the use in the treatment of skin lesions for example due topemphigus vulgaris, dermatitis herpetiformis, pemphigoid and otherblistering skin conditions.

2.28 The use of a compound according to any one of Embodiments 1.1 to1.82 for the use in treating, preventing, ameliorating or reversingconditions associated with altered gastro-intestinal function andmotility such as functional dyspepsia, irritable bowel syndrome,gastroesophageal acid reflux (GER) and esophageal dysmotility, symptomsof gastroparesis and chronic diarrhea.

2.29 The use of a compound according to any one of Embodiments 1.1 to1.82 for the use in in the treatment of olfactory dysfunction such asBosma-Henkin-Christiansen syndrome, chemical poisoning (e.g. seleniumand silver), hypopituitarism, Kallmann Syndrome, skull fractures, tumourtherapy and underactive thyroid gland.

Methods for the Preparation of Compounds of the Formula (1)

Compounds of the formula (1) can be prepared in accordance withsynthetic methods well known to the skilled person and as describedherein.

Accordingly, in another embodiment (Embodiment 3.1), the inventionprovides a process for the preparation of a compound as defined in anyone of Embodiments 1.1 to 1.82, which process comprises:

(A) the reaction of a compound of the formula (10)

wherein R³, R⁴, R⁵, X₁ and X₂ are as defined in any one of Embodiments1.1 to 1.82 with a compound of the formula R¹R²NH under amide-formingconditions; or

(B) the reaction of a compound of the formula (11):

with (i) a compound of the formula Cl—C(═O)—CH²—R⁴, in the presence of abase; or (ii) a compound of the formula R⁴—CH₂—OH and triphosgene; or(iii) with 4-nitrophenyl chloroformate followed by a compound of theformula R⁴—CH₂—OH, in the presence of a base;

and optionally:

(C) converting one compound of the formula (1) to another compound ofthe formula (1).

In process variant (A), the reaction may be carried out in the presenceof a reagent of the type commonly used in the formation of amide bonds.Examples of such reagents include 1,3-dicyclohexylcarbodiimide (DCC)(Sheehan et al, J. Amer. Chem Soc. 1955, 77, 1067),1-ethyl-3-(3′-dimethylaminopropyl)-carbodiimide (referred to hereineither as EDC or EDAC) (Sheehan et al, J. Org. Chem., 1961, 26, 2525),uronium-based coupling agents such asO-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HATU) and phosphonium-based coupling agents such as1-benzo-triazolyloxytris-(pyrrolidino)phosphonium hexafluorophosphate(PyBOP) (Castro et al, Tetrahedron Letters, 1990, 31, 205).Carbodiimide-based coupling agents are advantageously used incombination with 1-hydroxy-7-azabenzotriazole (HOAt) (L. A. Carpino, J.Amer. Chem. Soc., 1993, 115, 4397) or 1-hydroxybenzotriazole (HOBt)(Konig et al, Chem. Ber, 103, 708, 2024-2034). A preferred amidecoupling agent is HATU.

The coupling reaction is typically carried out in a non-aqueous,non-protic solvent such as acetonitrile, dioxane, dimethylsulphoxide,dichloromethane, dimethylformamide or N-methylpyrrolidinone, or in anaqueous solvent optionally together with one or more miscibleco-solvents. The reaction can be carried out at room temperature or,where the reactants are less reactive at an appropriately elevatedtemperature, for example a temperature up to about 100° C., e.g. 50-80°C. The reaction may optionally be carried out in the presence of anon-interfering base, for example a tertiary amine such as triethylamineor N,N-diisopropylethylamine.

As an alternative, a reactive derivative of the carboxylic acid, e.g. ananhydride or acid chloride, may be used. The acid chloride is typicallyreacted with the compound of formula R¹R²NH in the presence of a basesuch as sodium bicarbonate. The acid chloride can be prepared usingstandard methods, for example by treatment of the acid with oxalylchloride in the presence of a catalytic amount of dimethylformamide.

Process variant (B) is typically carried out in an aprotic solvent suchas dichloromethane or dichloroethane in the presence of anon-interfering base such as triethylamine. The reaction may beconducted at room temperature.

Intermediate compounds of the formula (10) can be prepared by the seriesof reactions shown in Scheme 1 below.

In reaction Scheme 1, the piperidine ester (12, R″=ethyl or methyl) isreacted with the substituted ketone (13) under reductive aminationconditions. The reductive amination reaction is typically carried outwith mild heating (e.g. to a temperature of from about 40° C. to about70° C.) in the presence of either sodium cyanoborohydride in combinationwith zinc chloride or sodium triacetoxyborohydride in combination withtitanium isopropoxide in a solvent such as dichloromethane ordichloroethane containing acetic acid to give an intermediate estercompound (14) which is then selectively hydrolysed under mild conditionsusing lithium hydroxide or sodium hydroxide to give compound (10).

Compounds of the formula (11) can be prepared by the sequence ofreactions shown in Scheme 2 below.

In Scheme 2, the piperidine ester (12, R″=ethyl or methyl) is reactedwith the ketone (15) under reductive amination conditions of the typedescribed above to give an intermediate ester (not shown) which is thenselectively hydrolysed using lithium hydroxide to give the carboxylicacid (16). The carboxylic acid (16) is then reacted with an amine HNR¹R²under amide-forming conditions (see above) to give an intermediate amidecompound (not shown) which is then deprotected by removal of the Bocgroup by treatment with acid (e.g. trifluoroacetic acid indichloromethane) to give the compound (11).

Compounds of the formula (10) can also be prepared by the sequence ofreactions shown in Scheme 3 below.

In Scheme 3, the substituted ketone (13) is reduced to the alcohol (17)using sodium borohydride in methanol. The alcohol (17) is then activatedas the sulfonic ester (18, R=methyl, trifluormethyl or 4-methylphenyl)using the corresponding sulfonyl chloride in dichloromethane in thepresence of a tertiary amine such as triethylamine orN,N-diisopropylethylamine. The sulfonic ester (18) is reacted with thepiperidine ester (12, R″=ethyl or methyl) in a nucleophilic substitutionreaction which is typically carried out with mild heating (e.g. to atemperature of from about 40° C. to about 70° C.) either neat, with nosolvent, or in a suitable solvent such as tetrahydrofuran, acetonitrileor dimethylacetamide to give compound (14) which is then selectivelyhydrolysed under mild conditions using lithium hydroxide or sodiumhydroxide to give compound (10).

Once formed, one compound of the formula (1), or a protected derivativethereof, can be converted into another compound of the formula (1) bymethods well known to the skilled person. Examples of syntheticprocedures for converting one functional group into another functionalgroup are set out in standard texts such as Advanced Organic Chemistryand Organic Syntheses (see references above) or Fiesers' Reagents forOrganic Synthesis, Volumes 1-17, John Wiley, edited by Mary Fieser(ISBN: 0-471-58283-2).

In many of the reactions described above, it may be necessary to protectone or more groups to prevent reaction from taking place at anundesirable location on the molecule. Examples of protecting groups, andmethods of protecting and deprotecting functional groups, can be foundin Protective Groups in Organic Synthesis (T. Greene and P Wuts; 3rdEdition; John Wiley and Sons, 1999).

Compounds made by the foregoing methods may be isolated and purified byany of a variety of methods well known to those skilled in the art andexamples of such methods include recrystallisation and chromatographictechniques such as column chromatography (e.g. flash chromatography) andHPLC.

Pharmaceutical Formulations

While it is possible for the active compound to be administered alone,it is preferable to present it as a pharmaceutical composition (e.g.formulation).

Accordingly, in another embodiment (Embodiment 4.1) of the invention,there is provided a pharmaceutical composition comprising at least onecompound of the formula (1) as defined in any one of Embodiments 1.1 to1.82 together with at least one pharmaceutically acceptable excipient.

In one embodiment (Embodiment 4.2), the composition is a tabletcomposition.

In another embodiment (Embodiment 4.3), the composition is a capsulecomposition.

The pharmaceutically acceptable excipient(s) can be selected from, forexample, carriers (e.g. a solid, liquid or semi-solid carrier),adjuvants, diluents (e.g solid diluents such as fillers or bulkingagents; and liquid diluents such as solvents and co-solvents),granulating agents, binders, flow aids, coating agents,release-controlling agents (e.g. release retarding or delaying polymersor waxes), binding agents, disintegrants, buffering agents, lubricants,preservatives, anti-fungal and antibacterial agents, antioxidants,buffering agents, tonicity-adjusting agents, thickening agents,flavouring agents, sweeteners, pigments, plasticizers, taste maskingagents, stabilisers or any other excipients conventionally used inpharmaceutical compositions.

The term “pharmaceutically acceptable” as used herein means compounds,materials, compositions, and/or dosage forms which are, within the scopeof sound medical judgment, suitable for use in contact with the tissuesof a subject (e.g. a human subject) without excessive toxicity,irritation, allergic response, or other problem or complication,commensurate with a reasonable benefit/risk ratio. Each excipient mustalso be “acceptable” in the sense of being compatible with the otheringredients of the formulation.

Pharmaceutical compositions containing compounds of the formula (1) canbe formulated in accordance with known techniques, see for example,Remington's Pharmaceutical Sciences, Mack Publishing Company, Easton,Pa., USA.

The pharmaceutical compositions can be in any form suitable for oral,parenteral, topical, intranasal, intrabronchial, sublingual, ophthalmic,otic, rectal, intra-vaginal, or transdermal administration.

Pharmaceutical dosage forms suitable for oral administration includetablets (coated or uncoated), capsules (hard or soft shell), caplets,pills, lozenges, syrups, solutions, powders, granules, elixirs andsuspensions, sublingual tablets, wafers or patches such as buccalpatches.

Tablet compositions can contain a unit dosage of active compoundtogether with an inert diluent or carrier such as a sugar or sugaralcohol, eg; lactose, sucrose, sorbitol or mannitol; and/or a non-sugarderived diluent such as sodium carbonate, calcium phosphate, calciumcarbonate, or a cellulose or derivative thereof such as microcrystallinecellulose (MCC), methyl cellulose, ethyl cellulose, hydroxypropyl methylcellulose, and starches such as corn starch. Tablets may also containsuch standard ingredients as binding and granulating agents such aspolyvinylpyrrolidone, disintegrants (e.g. swellable crosslinked polymerssuch as crosslinked carboxymethylcellulose), lubricating agents (e.g.stearates), preservatives (e.g. parabens), antioxidants (e.g. BHT),buffering agents (for example phosphate or citrate buffers), andeffervescent agents such as citrate/bicarbonate mixtures. Suchexcipients are well known and do not need to be discussed in detailhere.

Tablets may be designed to release the drug either upon contact withstomach fluids (immediate release tablets) or to release in a controlledmanner (controlled release tablets) over a prolonged period of time orwith a specific region of the GI tract.

The pharmaceutical compositions typically comprise from approximately 1%(w/w) to approximately 95%, preferably % (w/w) active ingredient andfrom 99% (w/w) to 5% (w/w) of a pharmaceutically acceptable excipient(for example as defined above) or combination of such excipients.Preferably, the compositions comprise from approximately 20% (w/w) toapproximately 90% (w/w) active ingredient and from 80% (w/w) to 10% of apharmaceutically excipient or combination of excipients. Thepharmaceutical compositions comprise from approximately 1% toapproximately 95%, preferably from approximately 20% to approximately90%, active ingredient Pharmaceutical compositions according to theinvention may be, for example, in unit dose form, such as in the form ofampoules, vials, suppositories, pre-filled syringes, dragées, powders,tablets or capsules.

Tablets and capsules may contain, for example, 0-20% disintegrants, 0-5%lubricants, 0-5% flow aids and/or 0-99% (w/w) fillers/or bulking agents(depending on drug dose). They may also contain 0-10% (w/w) polymerbinders, 0-5% (w/w) antioxidants, 0-5% (w/w) pigments. Slow releasetablets would in addition typically contain 0-99% (w/w)release-controlling (e.g. delaying) polymers (depending on dose). Thefilm coats of the tablet or capsule typically contain 0-10% (w/w)polymers, 0-3% (w/w) pigments, and/or 0-2% (w/w) plasticizers.

Parenteral formulations typically contain 0-20% (w/w) buffers, 0-50%(w/w) cosolvents, and/or 0-99% (w/w) Water for Injection (WFI)(depending on dose and if freeze dried). Formulations for intramusculardepots may also contain 0-99% (w/w) oils.

The pharmaceutical formulations may be presented to a patient in“patient packs” containing an entire course of treatment in a singlepackage, usually a blister pack.

The compounds of the formula (1) will generally be presented in unitdosage form and, as such, will typically contain sufficient compound toprovide a desired level of biological activity. For example, aformulation may contain from 1 nanogram to 2 grams of active ingredient,e.g. from 1 nanogram to 2 milligrams of active ingredient. Within theseranges, particular sub-ranges of compound are 0.1 milligrams to 2 gramsof active ingredient (more usually from 10 milligrams to 1 gram, e.g. 50milligrams to 500 milligrams), or 1 microgram to 20 milligrams (forexample 1 microgram to 10 milligrams, e.g. 0.1 milligrams to 2milligrams of active ingredient).

For oral compositions, a unit dosage form may contain from 1 milligramto 2 grams, more typically 10 milligrams to 1 gram, for example 50milligrams to 1 gram, e.g. 100 milligrams to 1 gram, of active compound.

The active compound will be administered to a patient in need thereof(for example a human or animal patient) in an amount sufficient toachieve the desired therapeutic effect (effective amount). The preciseamounts of compound administered may be determined by a supervisingphysician in accordance with standard procedures.

EXAMPLES

The invention will now be illustrated, but not limited, by reference tothe specific embodiments described in the following examples.

Examples 1 to 32

The compounds of Examples 1 to 32 shown in Table 1 below have beenprepared. Their NMR and LCMS properties and the methods used to preparethem are set out in Table 3. The starting materials for each of theExamples are listed in Table 2.

TABLE 1

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

Example 7

Example 8

Example 9

Example 10

Example 11

Example 12

Example 13

Example 14

Example 15

Example 16

Example 17

Example 18

Example 19

Example 20

Example 21

Example 22

Example 23

Example 24

Example 25

Example 26

Example 27

Example 28

Example 29

Example 30

Example 31

Example 32General Procedures

Where no preparative routes are included, the relevant intermediate iscommercially available. Commercial reagents were utilized withoutfurther purification. Room temperature (rt) refers to approximately20-27° C. ¹H NMR spectra were recorded at 400 MHz on either a Bruker orJeol instrument. Chemical shift values are expressed in parts permillion (ppm), i.e. (δ)-values. The following abbreviations are used forthe multiplicity of the NMR signals: s=singlet, br=broad, d=doublet,t=triplet, q=quartet, quint=quintet, td=triplet of doublets, tt=tripletof triplets, qd=quartet of doublets, ddd=doublet of doublet of doublets,ddt=doublet of doublet of triplets, m=multiplet. Coupling constants arelisted as J values, measured in Hz. NMR and mass spectroscopy resultswere corrected to account for background peaks. Chromatography refers tocolumn chromatography performed using 60-120 mesh silica gel andexecuted under nitrogen pressure (flash chromatography) conditions. TLCfor monitoring reactions refers to TLC run using the specified mobilephase and the Silica gel F254 as a stationary phase from Merck.Microwave-mediated reactions were performed in Biotage Initiator or CEMDiscover microwave reactors.

Mass spectroscopy was carried out on Shimadzu LC-2010 EV, WatersZQ-2000, UPLC-Mass SQD-3100 or Applied Biosystem API-2000 spectrometersusing electrospray conditions as specified for each compound in thedetailed experimental section.

Preparative HPLC was typically carried out under the followingconditions, (Gilson Semi-Prep HPLC): Column: Phenomenex Gemini NX 5 μmC18 110A Axia (100×30 mm); Mobile phase: Solvent A: MeCN; Solvent B:Water containing a 0.1 or 0.2% solution of aqueous NH₃ (28%) and 5%MeCN; Gradient: 20 to 60% of Solvent A in Solvent B over 14.4 min, hold60% Solvent A in Solvent B for 1.6 min, 100% Solvent A for 1.6 minFlowrate: 30 mL/min; Detection wavelength: 210 nm.

LCMS experiments were typically carried out using electrosprayconditions as specified for each compound under the followingconditions:

Method A and B

Instruments: Waters Alliance 2795, Waters 2996 PDA detector, MicromassZQ; Column: Waters X-Bridge C-18, 2.5 micron, 2.1×20 mm or PhenomenexGemini-NX C-18, 3 micron, 2.0×30 mm; Gradient [time (min)/solvent D in C(%)]: Method A: 0.00/2, 0.10/2, 2.50/95, 3.50/95, 3.55/2, 4.00/2 orMethod B: 0.00/2, 0.10/2, 8.40/95, 9.40/95, 9.50/2, 10.00/2; Solvents:solvent C=2.5 L H₂O+2.5 mL ammonia solution; solvent D=2.5 L MeCN+135 mLH₂O+2.5 mL ammonia solution); Injection volume 3 uL; UV detection 230 to400 nM; column temperature 45° C.; Flow rate 1.5 mL/min.

Method C

Instruments: HP1100, HP DAD G1315A detector, Micromass ZQ; Column:Phenomenex Gemini-NX C-18, 3 micron, 2.0×30 mm; Gradient [time(min)/solvent D in C (%)]: Method C: 0.00/2, 0.10/2, 8.40/95, 9.40/95,9.50/2, 10.00/2; Solvents: solvent C=2.5 L H₂O+2.5 mL ammonia solution;solvent D=2.5 L MeCN+135 mL H₂O+2.5 mL ammonia solution); Injectionvolume 3 uL; UV detection 230 to 400 nM; column temperature 45° C.; Flowrate 1.5 mL/min.

Method D

Instruments: Waters Alliance 2795, Waters 2996 PDA detector, MicromassZQ; Column: Waters X-Bridge C-18, 2.5 micron, 2.1×20 μm, flow rate 1.0mL/min; inj volume 5 μL; 5-95% acetonitrile:water+0.1% ammoniumhydroxide.

Method E

Instruments: Waters 2695 Alliance, Micromass ZQ, 2996 PDA and a Varian385-LC ELSD, Column: XBridge C18 3×100 mm×3.5 μm, flow rate 1 mL/min;Inj volume 20 μL, 5-95% acetonirtile:water+2% formic acid

GC experiments were run under the following conditions:

Method F

Instruments: Agilent 6890, CP select 624 column; Inj 200° C., 10 psi H₂;Det 250° C., 25 mL/min H₂, 400 mL/min air; oven 35° C. (2 min) 8° C./minto 130° C. (4.1 min)

Method G

Instruments: Agilent 6890, CP select 624 column; Inj 200° C., 10 psi H₂;Det 250° C., 25 mL/min H₂, 400 ml/min air; oven 35° C. (2 min) 4° C./minto 130° C. (5.75 min) GC data in the experimental section are given inthe format: run time, retention time, percentage peak area.

Abbreviations

d=day(s)

DCM=dichloromethane

DIPEA=diisopropylethylamine

DMF=dimethylformamide

DMSO=dimethylsulfoxide

ES=electro spray ionisation

EtOAc=ethyl acetate

h=hour(s)

HPLC=high performance liquid chromatography

LC=liquid chromatography

MeCN=acetonitrile

MeOH=methanol

min=minute(s)

MS=mass spectrometry

NMR=nuclear magnetic resonance

rt=room temperature

sat.=saturated

sol.=solution

STAB=sodium triacetoxyborohydride

THF=tetrahydrofuran

TLC=thin layer chromatography

Prefixes n-, s-, i-, t- and tert- have their usual meanings: normal,secondary, iso, and tertiary.

General Synthetic Procedures

Route a

Typical Procedure for the Preparation of Amides Via STAB ReductiveAmination and HATU Coupling as Exemplified by the Preparation of Example1 Isomer 1, ethyl3-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-8-azabicyclo[3.2.1]octane-8-carboxylate

Ethyl piperidine-4-carboxylate (0.797 g, 0.78 mL 5.07 mmol) andN-ethoxycarbonylnortropinone (1.00 g, 5.07 mmol) were dissolved in DCM(30 mL) at rt and titanium isopropoxide (1.59 g, 1.7 mL, 5.58 mmol) wasadded. The reaction mixture was stirred at rt for 1.5 h. STAB (2.15 g,10.14 mmol) and acetic acid (0.2 mL) were added and the reaction mixturewas stirred at rt overnight under nitrogen. The reaction mixture wasquenched with the addition of water (4 mL) and diluted with DCM thenfiltered through a pad of celite. The filtrate was washed with sat.NaHCO₃ sol., sat. NaCl sol. and dried over MgSO₄. The solvents wereremoved in vacuo, and the residue was purified by column chromatography(normal phase, [Biotage SNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50mL per min, gradient 2% to 4.5% MeOH in DCM]) to give ethyl3-[4-(ethoxycarbonyl)piperidin-1-yl]-8-azabicyclo[3.2.1]octane-8-carboxylateas a separable mixture of isomers. Isomer 1 (0.549 g, 32%) as a lightyellow oil and isomer 2 (0.137 g, 8%) as a light yellow oil.

LCMS (Method A): Isomer 1 m/z 339 (M+H)⁺ (ES⁺), at 1.78 min, UVinactive.

LCMS (Method A): Isomer 2 m/z 339 (M+H)⁺ (ES⁺), at 1.68 min, UVinactive.

Isomer 1 of ethyl3-[4-(ethoxycarbonyl)piperidin-1-yl]-8-azabicyclo[3.2.1]octane-8-carboxylate(0.549 g, 1.62 mmol) was dissolved in THF (10 mL) at rt and 1 M LiOHsol. (1.62 mL) was added. The reaction mixture was stirred at rt for 2days. The pH was carefully adjusted to pH 6 by addition of concentratedhydrochloric acid, the solvents were removed in vacuo, to give1-[8-(ethoxycarbonyl)-8-azabicyclo[3.2.1]oct-3-yl]piperidine-4-carboxylicacid (0.50 g, 100%) as an off white solid.

LCMS (Method A): m/z 311 (M+H)⁺ (ES⁺), at 0.1 min, UV inactive

1-[8-(Ethoxycarbonyl)-8-azabicyclo[3.2.1]oct-3-yl]piperidine-4-carboxylicacid (0.50 g assumed 1.62 mmol) was dissolved in DMF (8 mL) and(1-methylcyclobutyl)amine hydrochloride (0.295 g, 2.44 mmol), HATU(0.926 g, 2.44 mmol) and DIPEA (1.05 g, 1.41 mL, 8.12 mmol) were added.The reaction mixture was stirred at rt for 60 h and the solvents wereremoved in vacuo. The residue was partitioned between DCM and sat.NaHCO₃ sol., the organic layer was washed with sat. NaCl sol. and passedthrough a phase separator cartridge. The solvents of the organicfiltrate were removed in vacuo, and the residue was purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 25 mL per min, gradient 0% to 10% MeOH in DCM]) to giveethyl3-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-8-azabicyclo[3.2.1]octane-8-carboxylateisomer 1 (0.208 g, 34%) as a light yellow gum.

Data in Table 3

Route b

Typical Procedure for the Preparation of Amides Via NaCNBH₃ ReductiveAmination and HATU Coupling, as Exemplified by the Preparation ofExample 5 Isomer 1, ethyl3-{4-methoxy-4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-8-azabicyclo[3.2.1]octane-8-carboxylate

4-Methoxypiperidine-4-carboxylic acid methyl ester hydrochloride (0.500g, 2.38 mmol) was dissolved in methanol (2 mL) and treated with K₂CO₃(0.329 g, 2.38 mmol) in a minimum of water to de-salt. The mixture wasconcentrated in vacuo and azeotroped to dryness with toluene. Theresidue and N-ethoxycarbonylnortropinone (0.470 g, 2.39 mmol) weredissolved in methanol (20 mL) and zinc chloride (0.975 g, 7.15 mmol) wasadded. The reaction mixture was stirred at 50° C., under a nitrogenatmosphere, for 2 h then cooled to rt. NaCNBH₃ (0.299 g, 4.77 mmol) wasadded and the reaction mixture was stirred at 50° C. overnight undernitrogen. The reaction mixture was cooled to rt and the solvents wereremoved in vacuo, the residue was diluted with DCM and treated with satNaHCO₃ sol., the resulting heterogeneous mixture was filtered through acelite pad and the filtrate was washed with sat. NaHCO₃ sol., sat NaClsol. and dried over MgSO₄. The solvents were removed in vacuo, and theresidue was purified by column chromatography (normal phase, [BiotageSNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 50 mL per min, gradient 0%to 10% MeOH in DCM]) to give ethyl3-[4-methoxy-4-(methoxycarbonyl)piperidin-1-yl]-8-azabicyclo[3.2.1]octane-8-carboxylateas a separable mixture of isomers. Isomer 1 (0.097 g, 12%) as a paleyellow oil and Isomer 2 (0.022 g, 2.5%) as a pale yellow oil.

LCMS (Method A): Isomer 1 m/z 355 (M+H)⁺ (ES⁺), at 1.47-1.50 min, UVinactive.

LCMS (Method A): Isomer 2 m/z 355 (M+H)⁺ (ES⁺), at 1.47 min, UVinactive.

Isomer 1 of ethyl3-[4-methoxy-4-(methoxycarbonyl)piperidin-1-yl]-8-azabicyclo[3.2.1]octane-8-carboxylate(0.097 g, 0.27 mmol) was dissolved in THF (5 mL) at rt and 1 M LiOH sol.(0.3 mL) was added. The reaction mixture was stirred at rt for 7 days.The pH was carefully adjusted to pH 6 by addition of concentratedhydrochloric acid, the solvents were removed in vacuo, to give1-[8-(ethoxycarbonyl)-8-azabicyclo[3.2.1]oct-3-yl]-4-methoxypiperidine-4-carboxylicacid (0.093 g, 100%) as an off white solid.

LCMS (Method A): m/z 341 (M+H)⁺ (ES⁺), at 0.83 min, UV inactive.

1-[8-(Ethoxycarbonyl)-8-azabicyclo[3.2.1]oct-3-yl]-4-methoxypiperidine-4-carboxylicacid (0.093 g, assumed 0.27 mmol) was dissolved in DMF (5 mL) and(1-methylcyclobutyl)amine hydrochloride (0.05 g, 0.411 mmol), HATU(0.156 g, 0.41 mmol) and DIPEA (0.177 g, 0.24 mL, 1.37 mmol) were added.The reaction mixture was stirred at rt for 60 h and the solvents wereremoved in vacuo. The residue was partitioned between DCM and sat.NaHCO₃ sol., the organic layer was washed with sat. NaCl sol. and dried(MgSO₄). The solvents were removed in vacuo, and the residue waspurified by column chromatography (normal phase, [Biotage SNAP cartridgeKP-sil 10 g, 40-63 μm, 60 Å, 25 mL per min, gradient 0% to 10% MeOH inDCM]) to give ethyl3-{4-methoxy-4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-8-azabicyclo[3.2.1]octane-8-carboxylateisomer 1 (0.028 g, 25%) as a pale yellow gum.

Data in Table 3

Route c

Typical Procedure for the Preparation of Carbamates Via ChloroformateCoupling, as Exemplified by the Preparation of Example 9, ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate

Ethyl piperidine-4-carboxylate (0.35 g, 0.32 mL, 2.22 mmol) and6-azaspiro[3.4]octane-6-carboxylic acid, 2-oxo-, 1,1-dimethylethyl ester(0.500 g, 2.22 mmol) were dissolved in DCM (20 mL) at rt and titaniumisopropoxide (4.12 g, 4.40 mL, 14.5 mmol) was added. The reactionmixture was stirred at rt for 1 h. STAB (0.694 g, 0.72 mL, 2.44 mmol)and acetic acid (0.05 mL) were added and the reaction mixture wasstirred at rt overnight under nitrogen. The reaction mixture wasquenched with the addition of sat NaHCO₃ sol (5 mL) and stirred for 5minutes. The reaction mixture was diluted with DCM and filtered througha pad of celite. The filtrate was separated and washed with sat NaClsol. and dried over MgSO₄. The solvents were removed in vacuo, and theresidue was purified by column chromatography (normal phase, [BiotageSNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50 mL per min, gradient 0%to 5% MeOH in DCM)] to give tert-butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 90.9%) as a pale yellow oil.

LCMS (Method A): m/z 367 (M+H)⁺ (ES⁺), at 1.94/1.99 min, UV inactive

tert-Butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 2.02 mmol) was dissolved in THF (10 mL) at rt and 1 M LiOHsol. (2.02 mL) was added. The reaction mixture was stirred at rtovernight. The reaction mixture was adjusted to pH 5 by addition of 1 MHCl sol. and solvents were removed in vacuo, to give1-[6-(tert-butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid, which was used crude in the subsequent reaction.

LCMS (Method A): m/z 339 (M+H)⁺ (ES⁺), at 0.12 min, UV inactive

1-[6-(tert-Butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid was dissolved in DMF (5 mL) and (1-methylcyclobutyl)aminehydrochloride (0.37 g, 3.03 mmol), HATU (0.844 g, 2.22 mmol) and DIPEA(1.305 g, 10.1 mmol) were added. The reaction mixture was stirred at rtovernight under nitrogen. The solvents were removed in vacuo, and theresidue was partitioned between DCM and sat NaHCO₃ sol., organic layerwashed with sat NaCl sol. and dried over MgSO₄. The solvents wereremoved in vacuo, and the residue was purified by column chromatography(normal phase, [Biotage SNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50mL per min, gradient 0% to 10% MeOH in DCM]) to give tert-butyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.627 g, 76.7%) as a white foam.

LCMS (Method A): m/z 406 (M+H)⁺ (ES⁺), at 1.81 min, UV inactive

tert-Butyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.627 g, 1.55 mmol) was dissolved in DCM (8 mL) and TFA (2 mL) wasadded. The reaction mixture was stirred at rt overnight under nitrogen,then the solvents were removed in vacuo, to give1-(6-azaspiro[3.4]oct-2-yl)-N-(1-methylcyclobutyl)piperidine-4-carboxamidetrifluoroacetate as a dark yellow oil which was used directly withoutfurther purification. The residue was dissolved in DCM (10 mL) and NEt₃(0.49 g, 0.65 mL, 4.64 mmol) and ethyl chloroformate (0.25 mg, 0.18 mL,0.57 mmol) were added and the reaction mixture was stirred at rtovernight under nitrogen. The solvents were removed in vacuo, and theresidue was partitioned between DCM and sat NaHCO₃ sol., organic layerwashed with sat NaCl sol. and dried over MgSO₄. The residue was purifiedby column chromatography (normal phase, [Biotage SNAP cartridge KP-sil10 g, 40-63 μm, 60 Å, 12 mL per min, gradient 0% to 10% MeOH in DCM]) togive ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.04 g, 13%) as a yellow gum as a mixture of diastereomers.

Data in Table 3

Route d

Typical Procedure for the Preparation of Single Diastereoisomers,Followed by Chloroformate Coupling, as Exemplified by the Preparation ofExample 9 Isomer 2, ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate

6-Azaspiro[3.4]octane-6-carboxylic acid, 2-oxo-, 1,1-dimethylethyl ester(3.00 g, 13.33 mmol) was reduced to the alcohol, reacted undermesylation conditions and the resulting diastereoisomers were separatedin accordance with information detailed in patent WO 2010/089510, toproduce tert-butyl2-[(methylsulfonyl)oxy]-6-azaspiro[3.4]octane-6-carboxylate isomer 1(1.79 g, 44% over two steps) as a white crystalline solid and isomer 2(0.965 g, 24% over two steps) as a white crystalline solid.

LCMS (Method B): Isomer 1; m/z 306 (M+H)⁺ (ES⁺), at 3.36 min, UVinactive

LCMS (Method B): Isomer 2; m/z 306 (M+H)⁺ (ES⁺), at 3.39 min, UVinactive

tert-Butyl 2-[(methylsulfonyl)oxy]-6-azaspiro[3.4]octane-6-carboxylateisomer 1 (1.79 g, 5.73 mmol) and ethyl isonipecotate (4.49 g, 28.62mmol) were heated together to 65° C. for 5 days. The reaction mixturewas reduced in volume in vacuo, and the residue was purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 100 g,40-63 μm, 60 Å, 50 mL per min, gradient 1% to 4.5% MeOH in DCM]) to givetert-butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.264 g, 12.5%) as a yellow oil.

LCMS (Method A): m/z 367 (M+H)⁺ (ES⁺), at 1.97 min, UV inactive.

tert-Butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.080 g, 0.22 mmol) was stirred in DCM (10 mL) at rt and treated with 4M HCl/dioxane (1 mL). The reaction mixture was stirred overnight at roomtemperature. The reaction mixture was conc. in vacuo to give a yellowsolid that was used directly without further purification. The residuewas dissolved in DCM (10 mL) and NEt₃ (0.066 g, 0.1 mL, 0.66 mmol) andethyl chloroformate (0.036 g, 0.03 mL, 0.32 mmol) were added and thereaction mixture was stirred at rt overnight under nitrogen. Thesolvents were removed in vacuo, and the residue was partitioned betweenDCM and sat. NaHCO₃ sol., organic layer washed with sat. NaCl sol. anddried over MgSO₄. The residue was purified by column chromatography(normal phase, [Biotage SNAP cartridge KP-sil 10 g, 40-63 μm, 60 Å, 12mL per min, gradient 0% to 8% MeOH in DCM]) to give ethyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.069 g, 93%) as an amber oil.

LCMS (Method A): m/z 339 (M+H)⁺ (ES⁺), at 1.71 min, UV inactive.

Ethyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.069 g, 0.20 mmol) was dissolved in THF (4 mL) at rt and 1 M LiOH sol.(0.31 mL) was added. The reaction mixture was stirred at rt over theweekend. The reaction mixture was adjusted to pH 5 by addition of 1 MHCl sol. and solvents were removed in vacuo, to give1-[6-(ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid which was used directly without further purification.

LCMS (Method A): m/z 311 (M+H)⁺ (ES⁺), at 0.10 min, UV inactive.

1-[6-(Ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid (0.368 g, 1.10 mmol) was dissolved in DMF (8 mL) and(1-methylcyclobutyl)amine hydrochloride (0.200 g, 1.64 mmol), HATU(0.458 g, 1.21 mmol) and DIPEA (0.708 g, 5.45 mmol) were added. Thereaction mixture was stirred at rt overnight under nitrogen. Thesolvents were removed in vacuo, and the residue was partitioned betweenDCM and sat. NaHCO₃ sol., organic layer washed with sat. NaCl sol. anddried over MgSO₄. The solvents were removed in vacuo, and the residuewas purified by column chromatography (normal phase, [Biotage SNAPcartridge KP-sil 25 g, 40-63 μm, 60 Å, 12 mL per min, gradient 1% to 8%MeOH in DCM]) to give ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateisomer 2 (0.147 g, 35.5%) as a white foam.

Data in Table 3

Route e

Typical Procedure for the Preparation of Amides Via NaCNBH₃ ReductiveAmination and Acid Chloride Coupling, as Exemplified by the Preparationof Example 11, ethyl2-{4-fluoro-4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate

Ethyl-4-fluoropiperidine-4-carboxylate hydrochloride (0.376 g, 1.77mmol) was dissolved in methanol (5 mL) and treated with K₂CO₃ (0.244 g,1.77 mmol) in a minimum of water to de-salt. The mixture wasconcentrated in vacuo and azeotroped to dryness with toluene. Theresidue was dissolved in methanol (10 mL) and zinc chloride (0.969 g,7.11 mmol) was added. The reaction mixture was stirred at 50° C., undera nitrogen atmosphere, for 2 h then cooled to rt. NaCNBH₃ (0.222 g, 3.54mmol) was added and the reaction mixture was stirred at 50° C. overnightunder nitrogen. The reaction mixture was cooled to rt and the solventswere removed in vacuo, the residue was diluted with DCM and treated withsat. NaHCO₃ sol., the resulting heterogeneous mixture was filteredthrough a celite pad and the filtrate was washed with sat NaHCO₃ sol.,sat. NaCl sol. and dried over MgSO₄. The solvents were removed in vacuo,and the residue was purified by column chromatography (normal phase,[Biotage SNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 50 mL per min,gradient 1% to 9% MeOH in DCM]) to give tert-butyl2-[4-fluoro-4-(methoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.300 g, 46%) as a colourless oil.

LCMS (Method A): m/z 371 (M+H)⁺ (ES⁺), at 1.79 and 1.82 min, UVinactive.

Transesterification occurs under these reaction conditions.

tert-Butyl2-[4-fluoro-4-(methoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.300 g, 0.81 mmol) was dissolved in DCM (4 mL) and TFA (1 mL) wasadded. The reaction mixture was stirred at rt overnight under nitrogen,then the solvents were removed in vacuo, to give ethyl1-(6-azaspiro[3.4]oct-2-yl)-4-fluoropiperidine-4-carboxylatetrifluoroacetate, as a dark yellow oil which was used directly withoutfurther purification. The residue was dissolved in DCM (8 mL) at rt.NEt₃ (0.246 g, 0.34 mL, 2.43 mmol) and ethyl chloroformate (0.176 g,0.16 mL, 1.62 mmol) were added and the reaction mixture was stirred atrt overnight under nitrogen. The reaction mixture was partitionedbetween DCM and sat. NaHCO₃ sol., organic layer washed with sat NaClsol. and dried over MgSO₄. The residue was purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 10 g, 40-63μm, 60 Å, 12 mL per min, gradient 0% to 10% MeOH in DCM]) to give ethyl2-[4-fluoro-4-(methoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate (0.440 g, 158%impure) as a pale yellow oil.

LCMS (Method A): m/z 343 (M+H)⁺ (ES⁺), at 1.56 and 1.59 min, UVinactive.

Ethyl 2-[4-fluoro-4-(methoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate (assumed 0.81 mmol)was dissolved in THF (5 mL) at rt and 1 M LiOH sol. (0.81 mL) was added.The reaction mixture was stirred at rt for 2 days. The pH was carefullyadjusted to pH 6 by addition of concentrated hydrochloric acid, thesolvents were removed in vacuo, to give1-[6-(ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]-4-fluoropiperidine-4-carboxylicacid as an off white solid, which was used directly without furtherpurification.

LCMS (Method A): m/z 329 (M+H)⁺ (ES⁺), at 0.79 and 0.86 min, UVinactive.

Crude1-[6-(ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]-4-fluoropiperidine-4-carboxylicacid was suspended in thionyl chloride (3 mL) and the reaction wasstirred at 90° C. for 2 h. The reaction mixture was cooled to rt andconcentrated in vacuo. The residue was dissolved in DCM (5 mL) and(1-methylcyclobutyl)amine hydrochloride (0.196 g, 1.62 mmol) and DIPEA(0.523 g, 0.71 mL, 4.05 mmol) were added, the reaction mixture wasstirred overnight at rt. The reaction mixture was partitioned betweenDCM and sat NaHCO₃ sol., organic layer washed with sat. NaCl sol. anddried over MgSO₄. The residue was purified by column chromatography(normal phase, [Biotage SNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 12mL per min, gradient 0% to 6% MeOH in DCM]) to give ethyl2-{4-fluoro-4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl)}-azaspiro[3.4]octane-6-carboxylate(0.09 g, 28%) as a pale yellow gum as a mixture of diastereomers.

Data in Table 3

Route f

Typical Procedure for the Preparation of Amides, Followed byChloroformate Coupling, as Exemplified by the Preparation of Example 14,ethyl2-[4-(tert-butylcarbamoyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate

Ethyl piperidine-4-carboxylate (0.35 g, 0.32 mL, 2.22 mmol) and6-azaspiro[3.4]octane-6-carboxylic acid, 2-oxo-, 1,1-dimethylethyl ester(0.500 g, 2.22 mmol) were dissolved in DCM (20 mL) at rt and titaniumisopropoxide (4.12 g, 4.40 mL, 14.5 mmol) was added. The reactionmixture was stirred at rt for 1 h. STAB (0.694 g, 0.72 mL, 2.44 mmol)and acetic acid (0.05 mL) were added and the reaction mixture wasstirred at rt overnight under nitrogen. The reaction mixture wasquenched with the addition of sat. NaHCO₃ sol (5 mL) and stirred for 5minutes. The reaction mixture was diluted with DCM and filtered througha pad of celite. The filtrate was separated and washed with sat. NaClsol. and dried over MgSO₄. The solvents were removed in vacuo, and theresidue was purified by column chromatography (normal phase, [BiotageSNAP cartridge KP-sil 50 g, 40-63 tam, 60 Å, 50 mL per min, gradient 0%to 5% MeOH in DCM]) to give tert-butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 90.9%) as a pale yellow oil.

LCMS (Method A): m/z 367 (M+H)⁺ (ES⁺), at 1.94/1.99 min, UV inactive

tert-Butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 2.02 mmol) was dissolved in THF (10 mL) at rt and 1 M LiOHsol. (2.02 mL) was added. The reaction mixture was stirred at rtovernight. The reaction mixture was adjusted to pH 5 by addition of 1 MHCl sol. and solvents were removed in vacuo, to give1-[6-(tert-butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid, which was used crude in the subsequent reaction.

LCMS (Method A): m/z 339 (M+H)⁺ (ES⁺), at 0.12 min, UV inactive

1-[6-(tert-Butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid was dissolved in DMF (2 mL) and t-butylamine (0.087 g, 1.20 mmol),HATU (0.227 g, 0.60 mmol) and DIPEA (0.193 g, 1.50 mmol) were added. Thereaction mixture was stirred at rt overnight under nitrogen. Thesolvents were removed in vacuo, and the residue was partitioned betweenDCM and sat. NaHCO₃ sol., organic layer washed with sat. NaCl sol. anddried over MgSO₄. The solvents were removed in vacuo, and the residuewas purified by column chromatography (normal phase, [Biotage SNAPcartridge KP-sil 10 g, 40-63 μm, 60 Å, 12 mL per min, gradient 0% to 10%MeOH in DCM]) to givetert-butyl-2-[4-(tert-butylcarbamoyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.071 g, 60.5%) as a yellow oil.

LCMS (Method A): m/z 394 (M+H)⁺ (ES⁺), at 1.79 min, UV inactive

tert-Butyl-2-[4-(tert-butylcarbamoyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.627 g, 1.55 mmol) was dissolved in DCM (4 mL) and TFA (1 mL) wasadded. The reaction mixture was stirred at rt overnight under nitrogen,then the solvents were removed in vacuo, to give1-(6-azaspiro[3.4]oct-2-yl)-N-tert-butylpiperidine-4-carboxamidetrifluoroacetate (1:2) as an oil which was used directly without furtherpurification. The residue was dissolved in DCM (8 mL) and NEt₃ (0.056 g,0.08 mL, 0.54 mmol) and ethyl chloroformate (0.024 mg, 0.02 mL, 0.22mmol) were added and the reaction mixture was stirred at rt overnightunder nitrogen. The solvents were removed in vacuo, and the residue waspartitioned between DCM and sat. NaHCO₃ sol., organic layer washed withsat. NaCl sol. and dried over MgSO₄. The residue was purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 10 g, 40-63μm, 60 Å, 12 mL per min, gradient 0% to 10% MeOH in DCM]) to give ethyl2-[4-(tert-butylcarbamoyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.027 g, 41%) as an off-white solid as a mixture of diastereomers.

Data in Table 3

Route a

Alternative Procedure for the Preparation of Carbamates Via AmideCoupling, as Exemplified by the Preparation of Example 13, ethyl2-{4-[(2-methylpropyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate

Ethyl piperidine-4-carboxylate (0.35 g, 0.32 mL, 2.22 mmol) and 6azaspiro[3.4]octane-6-carboxylic acid, 2-oxo-, 1,1-dimethylethyl ester(0.500 g, 2.22 mmol) were dissolved in DCM (20 mL) at rt and titaniumisopropoxide (4.12 g, 4.40 mL, 14.5 mmol) was added. The reactionmixture was stirred at rt for 1 h. STAB (0.694 g, 0.72 mL, 2.44 mmol)and acetic acid (0.05 mL) were added and the reaction mixture wasstirred at rt overnight under nitrogen. The reaction mixture wasquenched with the addition of sat. NaHCO₃ sol (5 mL) and stirred for 5minutes. The reaction mixture was diluted with DCM and filtered througha pad of celite. The filtrate was separated and washed with sat. NaClsol. and dried over MgSO₄. The solvents were removed in vacuo, and theresidue was purified by column chromatography (normal phase, [BiotageSNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50 mL per min, gradient 0%to 5% MeOH in DCM]) to give tert-butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 90.9%) as a pale yellow oil.

LCMS (Method A): m/z 367 (M+H)⁺ (ES⁺), at 1.94/1.99 min, UV inactive

tert-Butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(3.00 g, 8.20 mmol) was dissolved in DCM (40 mL) and stirred with 4 MHCl in Dioxan (10 mL) at rt overnight. The reaction mixture was conc. invacuo to give ethyl 1-(6-azaspiro[3.4]oct-2-yl)piperidine-4-carboxylatetrifluoroacetate (1:2) as a pale pink solid which was used in the nextstep without further purification. Ethyl1-(6-azaspiro[3.4]oct-2-yl)piperidine-4-carboxylate trifluoroacetate(1:2) residue was dissolved in DCM (40 mL) and NEt₃ (2.49 g, 3.42 mL,24.6 mmol) and ethyl chloroformate (1.07 g, 0.93 mL, 9.84 mmol) wereadded and the reaction mixture was stirred at rt overnight undernitrogen. The solvents were removed in vacuo, and the residue waspartitioned between DCM and sat NaHCO₃ sol., organic layer washed withsat. NaCl sol. and dried over MgSO₄. The residue was purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 50 g, 40-63μm, 60 Å, 50 mL per min, gradient 0% to 10% MeOH in DCM]) to give ethyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(2.474 g, 89%) as an orange oil.

LCMS (Method A): m/z 339 (M+H)⁺ (ES⁺), at 1.67/1.71 min, UV inactive.

Ethyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(2.474 g, 7.32 mmol) was dissolved in THF (25 mL) at rt and 1 M LiOHsol. (7.32 mL) was added. The reaction mixture was stirred at rt overthe weekend. The reaction mixture was adjusted to pH 5 by addition of 1M HCl sol. and solvents were removed in vacuo, to give1-[6-(ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid which was used directly without further purification.

LCMS (Method A): m/z 311 (M+H)⁺ (ES⁺), at 0.85/0.91 min, UV inactive.

1-[6-(Ethoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid (0.200 g, 0.65 mmol) was dissolved in DMF (5 mL) isobutylamine(0.071 g, 0.97 mmol), HATU (0.270 g, 0.71 mmol) and DIPEA (0.417 g, 3.23mmol) were added. The reaction mixture was stirred at rt overnight undernitrogen. The solvents were removed in vacuo, and the residue waspartitioned between DCM and sat. NaHCO₃ sol., organic layer washed withsat. NaCl sol. and dried over MgSO₄. The solvents were removed in vacuo,and the residue was purified by column chromatography (normal phase,[Biotage SNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 12 mL per min,gradient 0% to 10% MeOH in DCM]) to give ethyl2-{4-[(2-methylpropyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.089 g, 37.7%) as a pale yellow gum as a mixture of diastereomers.

Data in Table 3

Route h

Alternative Procedure for the Preparation of Carbamates Via Para-NitroPhenylcarbamate Activation, as Exemplified by the Preparation of Example25, (2,2,2-trideutero)ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate

Ethyl piperidine-4-carboxylate (0.35 g, 0.32 mL, 2.22 mmol) and 6azaspiro[3.4]octane-6-carboxylic acid, 2-oxo-, 1,1-dimethylethyl ester(0.500 g, 2.22 mmol) were dissolved in DCM (20 mL) at rt and titaniumisopropoxide (4.12 g, 4.40 mL, 14.5 mmol) was added. The reactionmixture was stirred at rt for 1 h. STAB (0.694 g, 0.72 mL, 2.44 mmol)and acetic acid (0.05 mL) were added and the reaction mixture wasstirred at rt overnight under nitrogen. The reaction mixture wasquenched with the addition of sat. NaHCO₃ sol (5 mL) and stirred for 5minutes. The reaction mixture was diluted with DCM and filtered througha pad of celite. The filtrate was separated and washed with sat. NaClsol. and dried over MgSO₄. The solvents were removed in vacuo, and theresidue was purified by column chromatography (normal phase, [BiotageSNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50 mL per min, gradient 0%to 5% MeOH in DCM]) to give tert-butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 90.9%) as a pale yellow oil.

LCMS (Method A): m/z 367 (M+H)⁺ (ES⁺), at 1.94/1.99 min, UV inactive

tert-Butyl2-[4-(ethoxycarbonyl)piperidin-1-yl]-6-azaspiro[3.4]octane-6-carboxylate(0.739 g, 2.02 mmol) was dissolved in THF (10 mL) at rt and 1 M LiOHsol. (2.02 mL) was added. The reaction mixture was stirred at rtovernight. The reaction mixture was adjusted to pH 5 by addition of 1 MHCl sol. and solvents were removed in vacuo, to give1-[6-(tert-butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid, which was used crude in the subsequent reaction.

LCMS (Method A): m/z 339 (M+H)⁺ (ES⁺), at 0.12 min, UV inactive

1-[6-(tert-Butoxycarbonyl)-6-azaspiro[3.4]oct-2-yl]piperidine-4-carboxylicacid was dissolved in DMF (5 mL) and (1-methylcyclobutyl)aminehydrochloride (0.37 g, 3.03 mmol), HATU (0.844 g, 2.22 mmol) and DIPEA(1.305 g, 10.1 mmol) were added. The reaction mixture was stirred at rtovernight under nitrogen. The solvents were removed in vacuo, and theresidue was partitioned between DCM and sat. NaHCO₃ sol., organic layerwashed with sat. NaCl sol. and dried over MgSO₄. The solvents wereremoved in vacuo, and the residue was purified by column chromatography(normal phase, [Biotage SNAP cartridge KP-sil 50 g, 40-63 μm, 60 Å, 50mL per min, gradient 0% to 10% MeOH in DCM]) to give tert-butyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.627 g, 76.7%) as a white foam.

LCMS (Method A): m/z 406 (M+H)⁺ (ES⁺), at 1.81 min, UV inactive

tert-Butyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.747 g, 1.84 mmol) was dissolved in DCM (8 mL) and TFA (2 mL) wasadded. The reaction mixture was stirred at rt overnight under nitrogen,then the solvents were removed in vacuo, to give1-(6-azaspiro[3.4]oct-2-yl)-N-(1-methylcyclobutyl)piperidine-4-carboxamidetrifluoroacetate as a dark yellow oil which was used directly withoutfurther purification. The residue was dissolved in DCM (10 mL) and NEt₃(0.56 g, 0.77 mL, 5.52 mmol) and 4-nitrophenyl chloroformate (0.555 g,2.76 mmol) were added and the reaction mixture was stirred at rtovernight under nitrogen. The solvents were removed in vacuo, and theresidue was partitioned between DCM (15 mL) and 1 N NaOH sol. (15 mL).The aqueous layer was extracted with DCM (4×20 mL), dried over MgSO₄ andthe solvent evaporated. The residue was semi-purified by columnchromatography (normal phase, [Biotage SNAP cartridge KP-sil 25 g, 40-63μm, 60 Å, 25 mL per min, gradient 0% to 10% MeOH in DCM]) to give4-nitrophenyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.60 g, 69%) as a yellow gum as a mixture of diastereomers.

LCMS (Method C): m/z 471 (M+H)⁺ (ES⁺), at 4.60 min, UV active.

Ethanol-2,2,2-d3 (0.186 g, 0.22 mL, 3.78 mmol) was dissolved in THF(12.6 mL) and cooled 0° C. Sodium hydride (0.202 g, 5.044 mmol) wasadded and stirred for 1 h. 4-Nitrophenyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.600 g, 1.26 mmol) dissolved in THF (12.6 mL) was added and themixture stirred overnight under nitrogen. The mixture was partitionedbetween EtOAc (30 mL) and water (30 mL). The aqueous layer was extractedwith EtOAc (4×30 mL), dried over MgSO₄ and the solvent evaporated. Theresidue was semi-purified by column chromatography (normal phase,[Biotage SNAP cartridge KP-sil 25 g, 40-63 μm, 60 Å, 25 mL per min,gradient 0% to 10% MeOH in DCM]) to give ethyl-2,2,2-d32-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylate(0.240 g, 50%) as a yellow gum as a mixture of diastereomers. Separationof diastereomers was achieved via preparative HPLC to give(2,2,2-trideutero)ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateisomer 1 (0.094 g, 39%) as an off-white gum and isomer 2 (0.085 g, 35%)as an off-white gum.

Data in Table 3

Synthesis of Intermediates

Route i

Typical Procedure for the Preparation of Amines, as Exemplified by thePreparation of Intermediate 19, 1-(1,1,1-trideuteromethyl)cyclobutan-1-amine hydrochloride

Magnesium (2.67 g, 110 mmol) was stirred in dry ether in a three neckedflask fitted with a thermometer and dropping funnel.1,1,1-Trideuteromethyl iodide (6.24 mL, 100 mmol) in diethyl ether (40mL) was charged to the dropping funnel and a small crystal of iodineadded to the magnesium suspension. The magnesium suspension was warmedbriefly until the iodine colouration dissipated then the1,1,1-trideuteromethyl iodide solution added drop-wise (causing a smallexotherm). Once the addition was complete, the mixture was warmed to 32°C. for 30 mins then cooled to 0° C. Cyclobutanone (5 mL, 67 mmol) wasdissolved in diethyl ether (20 mL), dried over magnesium sulfate andfiltered. The solution was added drop-wise to the reaction mixture,keeping the temperature<15° C., then allowed to reach room temperatureovernight. The mixture was partitioned between aqueous ammonium chloride(100 mL) and diethyl ether (100 mL) and extracted 4 more times withether. The organic layer was dried over sodium sulfate and concentrated(250 mbar, 40° C.) to give a yellow oil (5.9 g, 75%).

¹H NMR (300 MHz, CDCl₃) δ: 1.41-1.52 (1H, m), 1.60-1.81 (2H, m),1.95-2.06 (4H, m).

Chloroacetonitrile (21.6 mL, 340 mmol) was added to a solution of1-(1,1,1-trideuteromethyl)cyclobutan-1-ol (10.14 g, 113.7 mmol) andacetic acid (3.1 mL). The mixture was cooled to 0° C. and concentratedsulfuric acid (18.3 mL) was added dropwise. Once the addition wascomplete the solution was allowed to reach room temperature and stirredfor 2 hours. The reaction was poured into ice/water (200 mL) andextracted with dichloromethane (3×150 mL). The organic layers werecombined, washed with aqueous sodium carbonate solution (100 mL) andbrine (100 mL), dried over sodium sulfate and concentrated to give ayellow oil. This oil was azeotroped with toluene to give a beige solid(19.7 g, 105%) which was used directly without purification.

¹H NMR (300 MHz, CDCl₃) δ: 1.79-1.90 (2H, m), 1.99-2.06 (2H, m),2.23-2.32 (2H, m), 3.94 (2H, s), 6.59 (1H, bs).

A solution of 2-chloro-N-(1-(1,1,1-trideuteromethyl)cyclobutyl)acetamide(10 g, 60.7 mmol) and thiourea (5.69 g, 74.8 mmol) in ethanol (45 mL)and acetic acid (6.1 mL) was refluxed overnight. The reaction mixturewas allowed to cool to room temperature and concentrated toapproximately 22 mL. The mixture was added to water (45 mL) and filteredto remove the precipitate. The filtrate was washed with diethyl ether(100 mL, discarded) then basified with NaOH (aq) to pH 13. The basiclayer was extracted with dichloromethane (4×100 mL), combined & driedover sodium sulfate and concentrated (200 mbar, 40° C.) to give a yellowoil (2.08 g). The oil was dissolved in diethyl ether (80 mL) and stirredwhilst HCl in diethyl ether (17 mL, 2 M) was added dropwise. Theresulting precipitate was filtered, washed with diethyl ether then driedunder vacuum at 40° C. to give 1-(1,1,1-trideuteromethyl)cyclobutan-1-amine hydrochloride (2.35 g, 31%).

¹H NMR (300 MHz, D₂O) δ: 1.79-1.89 (2H, m), 1.98-2.03 (2H, m), 2.15-2.25(2H, m).

¹³C NMR (300 MHz, D₂O) δ: 13.0, 22.5 (m), 32.0, 54.0.

Route j

Typical Procedure for the Preparation of Amines, as Exemplified by thePreparation of Intermediate 20, 1-(fluoromethyl)cyclobutan-1-aminehydrochloride

To a stirred solution of (methylsulfinyl)benzene (23.0 g, 164 mmol) inchloroform (80 mL) under argon at room temperature was addeddiethylaminosulfur trifluoride (43.0 mL, 328 mmol) dropwise and thereaction mixture was stirred for 2 days at this temperature then at 60°C. overnight. The mixture was added dropwise to a stirred solution ofsaturated aqueous sodium hydrogen carbonate at 0° C. then extracted 3times with dichloromethane. The combined organic layers were dried oversodium sulfate and concentrated to give (fluoromethyl)(phenyl)sulfane(20.0 g, 86%) as a yellow oil.

¹H NMR (300 MHz, CDCl₃) δ: 5.64 (s, 1H), 5.81 (s, 1H), 7.38-7.24 (m,3H), 7.53-7.46 (m, 2H).

To a stirred solution of (fluoromethyl)(phenyl)sulfane (20.0 g, 140mmol) in dichloromethane (300 mL) was added meta-chloroperoxybenzoicacid (84.0 g, 475 mmol) potionwise at 0° C. The reaction mixture wasallowed to warm slowly to room temperature and stirred overnight. Themixture was poured into a stirred solution of saturated aqueous sodiumhydrogen carbonate at 0° C., then extracted three times withdichloromethane. The combined organic layers were washed brine, driedover sodium sulfate and concentrated to give a yellow oil. The residuewas purified by flash column chromatography on silica (eluentheptane:ethyl acetate, 9:1 to 4:1) to give((fluoromethyl)sulfonyl)benzene (22.9 g, 93%) as a yellow oil.

¹H NMR (300 MHz, CDCl₃) δ: 5.05 (s, 1H), 7.63 (t, 2H), 7.73 (t, 1H),7.97 (d, 2H).

A mixture of titanium (IV) ethoxide (22.4 mL, 107 mmol) andcyclobutanone (5.37 mL, 71.0 mmoL) in tetrahydrofuran (120 mL) wasstirred for 10 minutes. Tert-butanesulfinamide (7.17 g, 59.0 mmol) wasadded and the reaction mixture was stirred at room temperature for 18hours. The mixture was concentrated and the residue dissolved in ethylacetate. The solution was washed with saturated aqueous sodium hydrogencarbonate, dried over sodium sulphate and concentrated to giveN-cyclobutylidene-2-methylpropane-2-sulfinamide (9.51 g, 77%) as a paleyellow oil which was used directly without purification.

¹H NMR (300 MHz, CDCl₃) δ: 1.18 (s, 9H), 2.12-1.97 (m, 2H), 3.10-3.00(m, 2H), 3.29-3.11 (m, 1H), 3.52-3.37 (m, 1H).

LCMS (Method D): m/z 174 (M+H)⁺ (ES⁺), at 1.10 min.

To a stirred solution of ((fluoromethyl)sulfonyl)benzene (5.0 g, 28.7mmol) in tetrahydrofuran (100 mL) at −78° C. under argon was addedn-butyl lithium (18.0 mL, 28.7 mmol) and the reaction mixture wasstirred for 40 minutes at this temperature.N-cyclobutylidene-2-methylpropane-2-sulfinamide (3.23 g, 18.7 mmol) wasadded to the mixture at −78° C. and the reaction mixture was allowed towarm slowly to room temperature and stirred overnight. The reactionmixture was quenched by the addition of water and extracted 3 times withdichloromethane. The combined organic layers were washed with brine,dried over sodium sulfate and concentrated to afford a brown oil. Theresidue was purified by flash column chromatography on silica (eluentheptane:ethyl acetate, 3:2 to 2:3) to giveN-(1-(fluoro(phenylsulfonyl)methyl)cyclobutyl)-2-methylpropane-2-sulfinamide(3.00 g, 33%) as a yellow oil.

¹H NMR (300 MHz, CDCl₃) δ: 1.27 (s, 9H), 1.96-1.82 (m, 1H), 2.14-2.00(m, 2H), 2.38-2.26 (m, 1H), 2.59-2.43 (m, 1H), 2.91-2.76 (m, 1H), 5.04(s, 1H), 5.53-5.55 (m, 1H), 7.52-7.55 (m, 2H), 7.62-7.65 (m, 1H),7.93-7.95 (m, 2H).

LCMS (Method D): m/z 348 (M+H)⁺ (ES⁺), at 1.54 min.

To a stirred solution ofN-(1-(fluoro(phenylsulfonyl)methyl)cyclobutyl)-2-methylpropane-2-sulfinamide(1.50 g, 4.32 mmol) in N,N-dimethylformamide (270 mL) was added a buffersolution of sodium acetate (22.6 g, 276 mmol) in acetic acid (34.6 mL)and the reaction mixture was stirred for 15 minutes at room temperature.Magnesium turnings (6.92 g, 289 mmol) were added and the mixture stirredat 65° C. for 24 hours. The mixture was treated with water and saturatedaqueous sodium hydrogen carbonate and extracted 3 times with ethylacetate. The combined organic layer was dried over sodium sulfate andconcentrated to give a yellow oil. The residue was purified by flashcolumn chromatography on silica (eluent: heptane:ethyl acetate 1:1 to0:1) to giveN-(1-(fluoromethyl)cyclobutyl)-2-methylpropane-2-sulfinamide (560 mg,53%) as a pale yellow oil.

¹H NMR (300 MHz, CDCl₃) δ: 1.20 (s, 9H), 1.99-1.68 (m, 2H), 3.62 (br s,1H), 4.36-4.38 (m, 1H), 4.52-4.54 (m, 1H).

To a stirred solution ofN-(1-(fluoromethyl)cyclobutyl)-2-methylpropane-2-sulfinamide (1.50 g,7.23 mmol) in methanol (20 mL) was added hydrochloric acid (20 mL, 7.23mmol, 4 M in dioxane) at 0° C. under argon and the reaction mixture wasallowed to warm to room temperature and stir for 1 hour. The mixture wasconcentrated and the crude product triturated in diethyl ether andtert-butyl methyl ether to give the desired product1-(fluoromethyl)cyclobutan-1-amine hydrochloride (0.90 g, 90%).

¹H NMR (300 MHz, CDCl₃) δ: 1.92-1.76 (m, 2H), 2.09-1.93 (m, 2H),2.36-2.16 (m, 2H), 4.54 (s, 1H), 4.70 (s, 1H), 8.68 (br s, 2H).

LCMS (Method D): m/z 104 (M+H)⁺ (ES⁺), at 1.31 min.

Route k

Typical Procedure for the Preparation of Amines, as Exemplified by thePreparation of Intermediate 21,1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutan-1-aminehydrochloride

Malonic acid-d4 (165 g, 1.53 mol), sulfuric acid-d2 (5.0 mL) andmethan(ol-d) (330 mL) in dichloromethane (825 mL) were stirred at roomtemperature for 4 days. Deuterium oxide (100 mL) was added and thephases separated. The aqueous phase was re-extracted withdichloromethane (100 mL). The combined organic phases were dried oversodium sulfate and concentrated to give a colourless oil. The residuewas purified by distillation (bp: 105° C. at 25 mmHg) to give thedesired product 2,2-dideuterio-malonic acid dimethyl ester (161 g, 79%)as a colourless oil.

¹H NMR (300 MHz, CDCl₃) δ: 3.76 (s, 6H).

¹³C NMR (300 MHz, CDCl₃) δ: 40.7, 52.6, 167.0.

GC (Method F): 20 min, at 11.91 min, 99.65%.

The reaction was carried out in 2 batches of 80.5 g. Lithium aluminiumdeuteride (40.0 g, 0.90 mol) was added portionwise to anhydroustetrahydrofuran (1.0 L) under argon and cooled to 0° C.2,2-Dideuterio-malonic acid dimethyl ester (80.5 g, 0.60 mol) inanhydrous tetrahydrofuran (300 mL) was added slowly maintaining thetemperature below 35° C. and the reaction mixture was stirred at roomtemperature overnight. Water (40 mL) was added cautiously followed bysodium hydroxide (40 mL, 15% aqueous solution), then further water (120mL) and the mixture was stirred at room temperature overnight. Themixture was filtered through celite washing withtetrahydrofuran:methanol (1:3, 1.0 L) and the filtrate was concentratedto give a crude residue (76.0 g). The aluminium salts were suspended inethyl acetate:methanol (2:1, 3.0 L), stirred for 1 hour, filtered andthe filtrate concentrated to give a further crop of crude residue (126g). The two residues were combined and purified by distillation to givethe desired product 1,1,2,2,3,3-hexadeuterio-propane-1,3-diol (56.0 g,57%).

¹³C NMR (300 MHz, CDCl₃) δ: 35.1, 57.6, 171.0

GC (Method F): 20 min, at 10.96 min, 99.22%.

The reaction was carried out in 2 batches. N-bromosuccinimide (196 g,1.10 mol) was added portionwise to a solution of1,1,2,2,3,3-hexadeuterio-propane-1,3-diol (28.0 g, 0.368 mol) andtriphenyl phosphine (289 g, 1.10 mol) in acetonitrile (500 mL) anddichloromethane (500 mL) keeping the temperature below 35° C. Thereaction mixture was stirred at room temperature overnight. Hexane (1 L)was added and the layers separated and re-extracted with hexane (400mL). The combined hexane layers were washed with sodium hydroxide (250mL, 2 M), then saturated aqueous sodium sulfite (200 mL), brine (200mL), dried over magnesium sulfate and concentrated. The residue wastriturated with heptane and the solid removed by filtration. Thefiltrate was concentrated and the residue triturated a second time withheptane. The solid was removed by filtration and the filtrates from eachbatch concentrated to give crude product (44.0 g and 34.0 grespectively). The combined residues were purified by distillation togive 1,1,2,2,3,3-hexadeuterio-1,3-dibromopropane (44.0 g, 62%).

GC (Method F): 20 min, at 12.10 min, 73.71%.

To a cooled suspension of sodium hydride (20.3 g, 508 mmol, 60%dispersion in oil) in dimethylsulfoxide (450 mL) and diethyl ether (110mL) was added a solution of 1,1,2,2,3,3-hexadeuterio-1,3-dibromopropane(44.0 g, 213 mmol) and p-toluenesulfonylmethyl isocyanide (33.4 g, 171mmol) in dimethylsulfoxide (100 mL) and diethyl ether (25 mL) dropwise.The reaction mixture was stirred at 0° C. for 15 minutes then warmed toroom temperature for 1 hour. During this time a solid precipitated andthe reaction mixture had set solid. Dimethylsulfoxide (200 mL) wasadded, the solid broken up and the mixture stirred for 3 hours. Water(500 mL) was added cautiously, the solid was collected by filtration anddried to give1-((1-isocyano-2,2,3,3,4,4-hexadeuterocyclobutane)sulfonyl)-4-methylbenzene(41.6 g, 80%) as a brown solid. Which was used without furtherpurification.

¹H NMR (400 MHz, CDCl₃) δ: 2.46 (s, 3H), 7.38-7.42 (m, 2H), 7.83-7.86(m, 2H).

¹³C NMR (300 MHz, CDCl₃) δ: 14.2, 21.9, 30.8, 73.9, 129.9, 130.6, 146.5,164.88.

To a solution of1-((1-isocyano-2,2,3,3,4,4-hexadeuterocyclobutane)sulfonyl)-4-methylbenzene(41.6 g, 172 mmol) in distilled sulfolane (120 mL) was added a cooledmixture of sulfuric acid-d2 (9.4 mL) and deuterium oxide (9.4 mL) in oneportion. The reaction mixture was subjected to high vacuum (usingpotassium carbonate and potassium hydroxide traps) and heated to 120° C.The product was collected in a cold finger before the pump. The crudeproduct was dissolved in diethyl ether and the phases separated. Theorganic layer was dried over sodium sulfate and concentrated keeping thewater bath at 40° C. and the pressure at 250 mbar to give2,2,3,3,4,4-hexadeuterocyclobutanone (5.45 g, 42%) as a pale yellow oil.

GC (Method F): 20 min, at 4.93 min, 99.03%.

To a stirred suspension of magnesium (8.70 g, 0.358 mol) and iodine (1crystal) in diethyl ether (25 mL) under argon was added a few drops of asolution of 1,1,1-trideuteromethyl iodide in diethyl ether and themixture was gently warmed for 1 minute until the colour dissipated. Theremaining 1,1,1-trideuteromethyl iodide (8.91 mL, 0.143 mol) in diethylether (25 mL) was added at a rate to control the exotherm and maintainthe reaction at a gentle reflux. After the addition was complete thereaction mixture was stirred at room temperature for 30 minutes thencooled to 0° C. A solution of 2,2,3,3,4,4-hexadeuterocyclobutanone (5.45g, 0.0720 mmol) in diethyl ether (25 mL) was added slowly during whichtime an exotherm to reflux occurred. The reaction mixture was stirred at0° C. for 30 minutes then at room temperature for 30 minutes. Themixture was quenched by the cautious addition of saturated aqueousammonium chloride, diluted with water (400 mL) then diethyl ether (400mL). The phases were separated and the aqueous phase was extracted withdiethyl ether (400 mL). The combined organic layers were washed withbrine, dried over sodium sulfate and carefully concentrated to give1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutanol (2.42 g,36%).

GC (Method F): 20 min, at 5.84 min, 96.38%.

To a cooled stirred solution of1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutanol (2.42 g,25.4 mmol) in 2-chloroacetonitrile (8.0 mL, 127 mmol) was added aceticacid-d4 (7.3 mL, 127 mmol) and sulfuric acid-d2 (4.2 mL, 76.3 mmol) andthe reaction mixture was warmed slowly to room temperature and stirredfor 3 hours. The mixture was added to ice and extracted withdichloromethane (2×30 mL). The combined organic layers were washed withaqueous sodium carbonate solution (30 mL), then brine, dried over sodiumsulfate and concentrated to give2-chloro-N-(1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl)acetamide(3.95 g, 91%).

LCMS (Method D): m/z 169 (M+H)⁺ (ES⁺), at 1.04 min.

To a stirred solution of2-chloro-N-(1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl)acetamide(8.52 g, 48.2 mol) in industrial methylated spirits (50 mL) and aceticacid (10 mL) was added thiourea (7.60 g, 99.8 mmol) and the reactionmixture was heated to reflux overnight. The solid was removed byfiltration and washed with industrial methylated spirits. Hydrochloricacid (10 mL, 2 M) was added to the filtrate then the industrialmethylated spirits was removed under reduced pressure. The residue waspartitioned between diethyl ether and water. The aqueous layer wasbasified to pH 10 by the addition of sodium hydroxide (2 M) andextracted with diethyl ether (3×50 mL). The combined organic layers weredried over sodium sulfate. Hydrochloric acid (4 M in dioxane) was addedand the mixture stirred for 1 hour at room temperature. The mixture wasconcentrated and azeotroped 3 times with toluene and isopropyl alcoholto give a pale yellow solid. The solid was triturated in diethyl etherand dried in a vacuum oven to give1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutan-1-aminehydrochloride (1.29 g, 43%).

LCMS (Method E): m/z 95 (M+H)⁺ (ES⁺), at 0.92 min.

GC (Method G): 30 min, at 20.56 min, 90.57%.

TABLE 2 Table 2 - Starting Materials and Intermediates Intermediate NameData 1 ethyl piperidine-4-carboxylate Commercially available, CAS:1126-09-6 2 ethyl 4-fluoropiperidine-4-carboxylate Commerciallyavailable, hydrochloride CAS: 845909-49-1 3 methyl4-methoxypiperidine-4-carboxylate Commercially available, hydrochlorideCAS: 1190314-13-6 4 ethyl 3-oxo-8-azabicyclo[3.2.1]octane-8-Commercially available, carboxylate CAS: 32499-64-2 5 tert-butyl3-oxo-8-azabicyclo[3.2.1]octane-8- Commercially available, carboxylateCAS: 185099-67-6 6 tert-butyl 3-oxo-9-azabicyclo[3.3.1]nonane-Commercially available, 9-carboxylate CAS: 512822-27-4 7 tert-butyl3-oxo-6-azabicyclo[3.2.1]octane-6- Commercially available, carboxylateCAS: 359779-74-1 8 tert-butyl 5-oxohexahydro Commercially available,cyclopenta[c]pyrrole-2(1H)-carboxylate CAS: 148404-28-8 9 tert-butyl2-oxo-6-azaspiro[3.4]octane-6- Commercially available, carboxylate CAS:203661-71-6 10 tert-butyl 6-oxo-2-azaspiro[3.4]octane-2- Commerciallyavailable, carboxylate CAS: 1363382-39-1 11 (1-methylcyclobutyl)aminehydrochloride Commercially available, CAS: 174886-05-6 12tert-butylamine Commercially available, CAS: 75-64-9 13 isobutylamineCommercially available, CAS: 78-81-9 14 1,1-dimethylpropylamineCommercially available, CAS: 594-39-8 15 cyclobutanamine Commerciallyavailable, CAS: 2516-34-9 16 cyclopentanamine Commercially available,CAS: 1003-03-8 17 cyclobutylmethylamine hydrochloride Commerciallyavailable, CAS: 5454-82-0 18 (1-methylcyclobutyl)methanamineCommercially available, hydrochloride CAS: 1245647-53-3 191-(fluoromethyl)cyclobutan-1-amine See experimental sectionhydrochloride 20 1-(1,1,1-trideuteromethyl) cyclobutan-1- Seeexperimental section amine hydrochloride 211-(1,1,1-trideuteromethyl)-2,2,3,3,4,4- See experimental sectionhexadeuterocyclobutan-1-amine hydrochloride 22 2-Fluoroethylchloroformate Commercially available, CAS: 462-27-1 23 Vinylchloroformate Commercially available, CAS: 5130-24-5 242,2,2-Trideuteroethanol Commercially available, CAS: 1759-87-1 251,1,2,2,2-Pentadeuteroethanol Commercially available, CAS: 1859-08-1

TABLE 3 Ex. No. Name Intermediate Synthetic method ¹H NMR LCMS MethodLCMS data 1 Isomer 1: ethyl 3-{4-[(1- 1, 4 and 11 a (500 MHz, DMSO-d₆)δ: 1.07-1.27 (m, 4H), 1.35 B m/z 378 (M + H)⁺ (ES⁺), at 3.31methylcyclobutyl)carbamoyl]piperidin-1-yl}- (s, 3H), 1.41-1.78 (m, 10H),1.78-2.17 (m, 7H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 2.09-2.31 (m, 3H), 2.65-3.18 (m,2H), 3.53-3.70 (m, 1H), 4.08 (q, J = 6.9, 2H), 4.17-4.22 (m, 2H), 8.96(br. s, 1H). 1 Isomer 2: ethyl 3-{4-[(1- 1, 4 and 11 a (500 MHz, DMSO-d₆δ: 1.09-1.24 (m, 3H), 1.30- B m/z 378 (M + H)⁺ (ES⁺), at 3.40methylcyclobutyl)carbamoyl]piperidin-1-yl}- 1.40 (m, 3H), 1.46-1.61 (m,2H), 1.65-1.67 (m, min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 2H), 1.68-1.80 (m, 5H),1.80-1.98 (m, 9H), 2.02- 2.06 (m, 1H), 2.13-2.36 (m, 3H), 3.06-3.26 (m,2H), 3.97-4.21 (m, 4H), 7.76 (br. s, 1H). 2 Isomer 1: prop-2-yn-1-yl3-{4-[(1- 1, 5 and 11 c (400 MHz, DMSO-d₆) δ: 1.32 (s, 3H), 1.39-1.78 Bm/z 388 (M + H)⁺ (ES⁺), at 3.30methylcyclobutyl)carbamoyl]piperidin-1-yl}- (m, 12H), 1.78-1.92 (m, 5H),1.92-2.08 (m, 3H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 2.11-2.26 (m, 2H), 2.78-2.82 (m,2H), 3.50- 3.54 (m, 1H), 4.13-4.18 (m, 2H), 4.65-4.69 (m, 2H), 7.70 (br.s, 1H). 2 Isomer 2: prop-2-yn-1-yl 3-{4-[(1- 1, 5 and 11 c (400 MHz,DMSO-d₆) δ: 1.33 (s, 3H), 1.42-1.58 B m/z 388 (M + H)⁺ (ES⁺), at 3.34methylcyclobutyl)carbamoyl]piperidin-1-yl}- (m, 2H), 1.58-1.81 (m, 7H),1.81-2.07 (m, 10H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 2.11-2.27 (m, 3H), 3.04-3.20 (m,2H), 3.49-3.53 (m, 1H), 4.06-4.10 (m, 2H), 4.66-4.68 (m, 2H), 7.73 (s,1H). 3 Isomer 1: but-2-yn-1-yl 3-{4-[(1- 1, 5 and 11 c (400 MHz,DMSO-d₆) δ: 1.32 (s, 3H), 1.37-1.65 B m/z 402 (M + H)⁺ (ES⁺), at 3.28methylcyclobutyl)carbamoyl]piperidin-1-yl}- (m, 7H), 1.65-1.80 (m, 5H),1.80-1.91 (m, 7H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 1.91-2.09 (m, 4H), 2.11-2.27 (m,2H), 2.80-2.84 (m, 3H), 4.38-4.42 (m, 1H), 4.57-4.61 (m, 2H), 7.70 (br.s, 1H). 3 Isomer 2: but-2-yn-1-yl 3-{4-[(1- 1, 5 and 11 c (400 MHz,DMSO-d₆) δ: 1.32 (s, 3H), 1.38-1.53 B m/z 402 (M + H)⁺ (ES⁺), at 3.54methylcyclobutyl)carbamoyl]piperidin-1-yl}- (m, 3H), 1.53-1.68 (m, 6H),1.68-1.78 (m, 3H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 1.78-1.92 (m, 7H), 1.97-2.00 (m,3H), 2.11-2.24 (m, 2H), 2.75-2.81 (m, 3H), 4.12-4.16 (m, 2H), 4.61-4.67(m, 2H), 7.70 (br. s, 1H). 4 Isomer 2: ethyl 3-{4-fluoro-4-[(1- 2, 4 and11 b (400 MHz, DMSO-d₆) δ: 1.18 (t, J = 7.0, 3H) 1.35 (s, B m/z 396 (M +H)⁺ (ES⁺), at 3.84 methylcyclobutyl)carbamoyl]piperidin-1-yl}- 3H),1.45-1.50 (m, 2H), 1.58-1.79 (m, 8H), 1.79- min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 2.05 (m, 6H), 2.13-2.36 (m, 4H),2.71 (d, J = 10.3, 2H), 2.82 (dt, J = 11.0, 5.7, 1H), 4.04 (q, J = 7.0,2H), 4.12-4.18 (m, 2H), 7.93 (br. s, 1H). 5 Isomer 1: ethyl3-{4-methoxy-4-[(1- 3, 5 and 11 b (400 MHz, DMSO-d₆) δ: 1.17 (t, J =7.0, 3H), 1.34 B m/z 408 (M + H)⁺ (ES⁺), at 3.52methylcyclobutyl)carbamoyl]piperidin-1-yl}- (s, 3H), 1.37-1.54 (m, 2H),1.67-1.79 (m, 11H), min, UV inactive8-azabicyclo[3.2.1]octane-8-carboxylate 1.79-1.95 (m, 4H), 2.12-2.31 (m,4H), 2.51-2.54 (m, 1H), 2.70-2.73 (m, 1H), 3.06 (s, 3H), 4.04 (q, J =7.0, 2H), 4.12-4.16 (m, 2H), 7.65 (br. s, 1H). 6 Mixture ofdiastereomers: ethyl 3-{4-[(1- 1, 6 and 11 c (400 MHz, DMSO-d₆) δ: 1.17t, J = 7.0, 3H), 1.32 (s, A m/z 392 (M + H)⁺ (ES⁺), at 1.67methylcyclobutyl)carbamoyl]piperidin-1-yl}- 3H), 1.47-1.53 (m, 5H),1.55-1.68 (m, 6H), 1.70- min, UV inactive9-azabicyclo[3.3.1]nonane-9-carboxylate 1.86 (m, 7H), 1.95-2.01 (m, 3H),2.11-2.24 (m, 2H), 2.86-2.90 (m, 2H), 3.08-3.12 (m, 1H), 4.03 (q, J =7.0, 2H), 4.19-4.24 (m, 2H), 7.71 (br. s, 1H). 7 Mixture ofdiastereomers: ethyl 3-{4-[(1- 1, 7 and 11 c (400 MHz, DMSO-d₆) δ:1.15-1.21 (m, 3H), 1.33 B m/z 378 (M + H)⁺ (ES⁺), at 3.14methylcyclobutyl)carbamoyl]piperidin-1-yl}- (s, 3H), 1.38-1.59 (m, 3H),1.59-1.79 (m, 7H), and 3.28 min, UV inactive6-azabicyclo[3.2.1]octane-6-carboxylate 1.79-2.08 (m, 6H), 2.11-2.27 (m,3H), 2.27-2.46 (m, 2H), 3.02-3.18 (m, 4H), 3.86-4.15 (m, 3H), 7.78 (br.s, 1H). 8 Mixture of diastereomers: ethyl 5-{4-[(1- 1, 8 and 11 c (400MHz, DMSO-d₆) δ: 1.16-1.21 (m, 5H), 1.30- B m/z 378 (M + H)⁺ (ES⁺), at3.37 methylcyclobutyl)carbamoyl]piperidin-1- 1.42 (m, 3H), 1.59-1.81 (m,5H), 1.81-1.97 (m, min, UV inactiveyl}hexahydrocyclopenta[c]pyrrole-2(1H)- 5H), 2.14-2.35 (m, 5H),2.57-2.61 (m, 2H), 2.77- carboxylate 2.89 (m, 1 H), 3.03-3.13 (m, 2H),3.40-3.53 (m, 4H), 4.02 (q, J = 7.0, 2H), 7.93-7.99 (m, 1H). 9 Mixtureof diastereomers: ethyl 2-{4-[(1- 1, 9 and 11 c (400 MHz, DMSO-d₆) δ:1.10-1.21 (m, 3H), 1.32 B m/z 378 (M + H)⁺ (ES⁺), at 3.31methylcyclobutyl)carbamoyl]piperidin-1-yl}- (s, 3H), 1.40-1.54 (m, 2H),1.57-1.61 (m, 4H), and 3.45 min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 1.68-1.90 (m, 8H), 1.90-2.08 (m,3H), 2.11-2.26 (m, 2H), 2.55-2.72 (m, 1H), 2.75-2.79 (m, 2H), 3.09-3.28(m, 4H), 3.88-4.09 (m, 2H), 7.73 (s, 1H). 9 Isomer 1: ethyl 2-{4-[(1- 1,9 and 11 d (400 MHz, CDCl₃) δ: 1.20-1.31 (m, 3H), 1.45 (s, B m/z 378(M + H)⁺ (ES⁺), at 3.31 methylcyclobutyl)carbamoyl]piperidin-1-yl}- 3H),1.72-1.96 (m, 9H), 1.97-2.18 (m, 8H), 2.18- min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 2.30 (m, 2H), 2.50-2.60 (m, 1H),2.89-3.01 (m, 2H), 3.23-3.44 (m, 4H), 4.14 (q, J = 7.0 Hz, 2H), 5.51(br. s, 1H). 9 Isomer 2: ethyl 2-{4-[(1- 1, 9 and 11 d (400 MHz, CDCl₃)δ: 1.20-1.29 (m, 3H), 1.45 (s, B m/z 378 (M + H)⁺ (ES⁺), at 3.45methylcyclobutyl)carbamoyl]piperidin-1-yl}- 3H), 1.68-1.97 (m, 9H),1.97-2.18 (m, 8H), 2.19- min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 2.29 (m, 2H), 2.77-2.95 (m, 1H),2.96-3.06 (m, 2H), 3.26-3.34 (m, 2H), 3.34-3.46 (m, 2H), 4.10 (q, J =7.0, 2H), 5.75 (br. s, 1H). 10 Mixture of diastereomers: but-2-yn-1-yl2-{4- 1, 9 and 11 c (400 MHz, DMSO-d₆) δ: 1.33 (s, 3H), 1.42-1.67 B m/z402 (M + H)⁺ (ES⁺), at 3.57 [(1-methylcyclobutyl)carbamoyl]piperidin-1-(m, 6H), 1.71-1.88 (m, 11H), 1.92-2.05 (m, 3H), and 3.67 min, UVinactive yl}-6-azaspiro[3.4]octane-6-carboxylate 2.17-2.23 (m, 2H),2.62-2.82 (m, 3H), 3.22- 3.31 (m, 4H), 4.59-4.62 (m, 2H), 7.72 (br. s,1H). 11 Mixture of diastereomers: ethyl 2-{4-fluoro- 2, 9 and 11 e (400MHz, DMSO-d₆) δ: 1.17 (t, J = 7.2, 3H), B m/z 396 (M + H)⁺ (ES⁺), at3.77 4-[(1-methylcyclobutyl)carbamoyl]piperidin- 1.36 (s, 3H), 1.67-1.85(m, 8H), 1.85-1.96 (m, 5H), and 3.90 min, UV inactive1-yl}-6-azaspiro[3.4]octane-6-carboxylate 1.97-2.04 (m, 3H), 2.12-2.30(m, 2H), 2.65-2.70 (m, 3H), 3.07-3.30 (m, 4H), 3.87-4.10 (m, 2H), 7.93(br. s, 1H). 12 Racemic: ethyl 6-{4-[(1- 1, 10 and 11 c (400 MHz,DMSO-d₆) δ: 1.15 (t, J = 7.0, 3H), B m/z 378 (M + H)⁺ (ES⁺), at 3.34methylcyclobutyl)carbamoyl]piperidin-1-yl}- 1.33 (s, 3H), 1.40-1.65 (m,6H), 1.71-1.87 (m, 10H), min, UV inactive2-azaspiro[3.4]octane-2-carboxylate 1.95-2.05 (m, 2H), 2.15-2.23 (m,2H), 2.80- 2.92 (m, 2H), 3.67-3.80 (m, 4H), 3.98 (q, J = 7.0, 2H), 7.69(br. s, 1H). 13 Racemic: prop-2-yn-1-yl 6-{4-[(1- 1, 10 and 11 c (400MHz, DMSO-d₆) δ: 1.33 (s, 3H), 1.42-1.88 B m/z 388 (M + H)⁺ (ES⁺), at3.31 methylcyclobutyl)carbamoyl]piperidin-1-yl}- (m, 15H), 2.08-2.23 (m,4H), 2.90-3.04 (m, 2H), min, UV inactive2-azaspiro[3.4]octane-2-carboxylate 3.50-3.51 (m, 1H), 3.71-3.84 (m,4H), 4.61- 4.63 (m, 2H), 7.76 (br. s, 1H). 14 Mixture of diastereomers:ethyl 2-[4-(tert- 1, 9 and 12 f (400 MHz, CDCl₃) δ: 1.21-1.27 (m, 3H),1.33 (s, B m/z 366 (M + H)⁺ (ES⁺), at 3.28butylcarbamoyl)piperidin-1-yl]-6- 9H), 1.75-2.25 (m, 13H), 2.65-2.80 (m,1H), 2.90- and 3.42 min, UV inactive azaspiro[3.4]octane-6-carboxylate3.02 (m, 2H), 3.25-3.45 (m, 4H), 4.05-4.16 (J = 7.0, 2H), 5.30 (br. s,1H). 15 Mixture of diastereomers: ethyl 2-{4-[(2- 1, 9 and 13 g (400MHz, CDCl₃) δ: 0.90 (d, J = 6.5 Hz, 6H), 1.22- B m/z 366 (M + H)⁺ (ES⁺),at 3.10 methylpropyl)carbamoyl]piperidin-1-yl}-6- 1.29 (m, 3H),1.72-1.98 (m, 10H), 2.01-2.20 (m, and 3.16 min, UV inactiveazaspiro[3.4]octane-6-carboxylate 4H), 2.63-2.75 (m, 1H), 2.89-2.99 (m,2H), 3.08 (t, J = 6.5 Hz, 2H), 3.22-3.45 (m, 4H), 4.08-4.15 (m, 2H),5.51 (br. s, 1H). 16 Mixture of diastereomers: ethyl 2-{4-[(2- 1, 9 and14 g (400 MHz, CDCl₃) δ: 0.82 (t, J = 7.5 Hz, 3H), 1.19- B m/z 380 (M +H)⁺ (ES⁺), at 3.54 methylbutan-2-yl)carbamoyl]piperidin-1-yl}- 1.32 (m,9H), 1.45 (m, 1H), 1.71 (q, J = 7.5 Hz, 2H), and 3.67 min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 1.77-2.00 (m, 6H), 2.01-2.30 (m,6H), 2.93- 3.11 (m, 3H), 3.26-3.44 (m, 4H), 4.08-4.15 (m, 2H), 5.36 (br.s, 1H). 17 Mixture of diastereomers: ethyl 2-[4- 1, 9 and 15 g (400 MHz,CDCl₃) δ: 1.16-1.31 (m, 3H), 1.40- B m/z 364 (M + H)⁺ (ES⁺), at 2.96(cyclobutylcarbamoyl)piperidin-1-yl]-6- 1.49 (m, 1H), 1.64-1.99 (m, 9H),2.00-2.09 (m, and 3.13 min, UV inactiveazaspiro[3.4]octane-6-carboxylate 2H), 2.10-2.25 (m, 5H), 2.25-2.42 (m,3H), 2.89- 3.12 (m, 3H), 3.29-3.47 (m, 3H), 4.18-4.15 (m, 2H), 4.26-4.40(m, 1H), 5.98 (br. s, 1 H). 18 Mixture of diastereomers: ethyl 2-[4- 1,9 and 16 g (400 MHz, CDCl₃) δ: 1.22-1.29 (m, 3H), 1.31- B m/z 378 (M +H)⁺ (ES⁺), at 3.23 (cyclopentylcarbamoyl)piperidin-1-yl]-6- 1.37 (m,2H), 1.70-1.81 (m, 3H), 1.81-2.06 (m, and 3.35 min, UV inactiveazaspiro[3.4]octane-6-carboxylate 12H), 2.06-2.36 (m, 4H), 2.74-2.89 (m,1H), 2.91- 3.03 (m, 2H), 3.19-3.45 (m, 4H), 4.02-4.28 (m, 3H), 5.53 (br.s, 1H). 19 Mixture of diastereomers: ethyl 2-{4- 1, 9 and 17 g (400 MHz,CDCl₃) δ: 1.21-1.29 (m, 3H), 1.40- B m/z 378 (M + H)⁺ (ES⁺), at 3.31[(cyclobutylmethyl)carbamoyl]piperidin-1-yl}- 1.50 (m, 1H), 1.60-1.72(m, 2H), 1.75-2.37 (m, and 3.46 min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 16H), 2.37-2.51 (m, 1H), 2.89-3.15(m, 3H), 3.22- 3.28 (m, 2H), 3.29-3.44 (m, 4H), 4.08-4.15 (m, 2H), 5.73(br. s, 1H). 20 Mixture of diastereomers: ethyl 2-(4-{[(1- 1, 9 and 18 g(400 MHz, CDCl₃) δ: 1.10 (s, 3H), 1.21-1.28 (m, B m/z 392 (M + H)⁺(ES⁺), at 3.61 methylcyclobutyl)methyl]carbamoyl}piperidin- 3H),1.49-1.57 (m, 1H), 1.65-1.72 (m, 2H), 1.79- and 3.73 min, UV inactive1-yl)-6-azaspiro[3.4]octane-6-carboxylate 2.48 (m, 16H), 2.75-2.85 (m,1H), 3.08-3.27 (m, 4H), 3.30-3.46 (m, 4H), 4.07-4.15 (m, 2H), 6.05 (br.s, 1H). 21 Isomer 2: ethyl 2-(4-{[1-(1,1,1- 1, 9 and 20 d (400 MHz,CDCl₃) δ: 1.21-1.35 (m, 3H), 1.51- B m/z 381 (M + H)⁺ (ES⁺), at 3.45trideuteromethyl)cyclobutyl]carbamoyl}piperidin- 2.39 (m, 19H),2.62-2.76 (m, 1H), 2.79-3.04 (m, min, UV inactive1-yl)-6-azaspiro[3.4]octane-6-carboxylate 2H), 3.22-3.51 (m, 4H),4.08-4.20 (m, 2H), 5.49 (br. s, 1H). 22 Isomer 2: ethyl 2-(4-{[1-(1,1,1-1, 9 and 21 d (400 MHz, CDCl₃) δ: 1.24 (t, J = 7.0, 3H), 1.56- C m/z 387(M + H)⁺ (ES⁺), at 3.84 trideuteromethyl)-2,2,3,3,4,4- 2.17 (m, 12H),2.58-2.81 (m, 1H), 2.81-3.00 (m, min, UV inactivehexadeuterocyclobutyl]carbamoyl}piperidin- 2H), 3.18-3.49 (m, 4H), 4.10(q, J = 7.0, 2H), 5.54 1-yl)-6-azaspiro[3.4]octane-6-carboxylate (br. s,1H). 23 Isomer 2: ethyl 2-(4-{[1- 1, 9 and 19 d (400 MHz, CDCl₃) δ:1.21-1.35 (m, 3H), 1.50- C m/z 396 (M + H)⁺ (ES⁺), at 3.79(fluoromethyl)cyclobutyl]carbamoyl}piperidin- 1.74 (m, 7H), 1.74-1.93(m, 5H), 1.93-2.08 (m, min, UV inactive1-yl)-6-azaspiro[3.4]octane-6-carboxylate 3H), 2.09 (m, 7 H), 2.34-3.55(m, 4H), 4.06-4.17 (q, J = 7.16, 2H), 4.58 (d, J = 48, 2H), exchangeableNH not observed. 24 Mixture of diastereomers: 2-fluoroethyl 2-{4- 1, 9,11 and 22 c (400 MHz, CDCl₃) δ: 1.44 (s, 3H), 1.66-2.15 (m, B m/z 396(M + H)⁺ (ES⁺), at 3.11 [(1-methylcyclobutyl)carbamoyl]piperidin-1-17H), 2.19-2.29 (m, 2H), 2.54-2.81 (m, 1H), 2.81- and 3.33 min, UVinactive yl}-6-azaspiro[3.4]octane-6-carboxylate 2.99 (m, 2H), 3.27-3.33(m, 1H), 3.34-3.48 (m, 3H), 4.23-4.31 (m, 1H), 4.33-4.40 (m, 1H), 4.50-4.58 (m, 1H), 4.62-4.70 (m, 1H), 5.51 (br. s, 1H). 25 Isomer 2:(2,2,2-trideutero)ethyl 2-{4-[(1- 1, 9, 11 and 24 h 400 MHz, CDCl₃) δ:1.45 (s, 3H), 1.54-2.33 (m, 18 C m/z 381 (M + H)⁺ (ES⁺), at 3.92methylcyclobutyl)carbamoyl]piperidin-1-yl}- H), 2.33-3.46 (m, 8H), 4.12(s, 2H), 5.37-6.23 min, UV inactive 6-azaspiro[3.4]octane-6-carboxylate(m, 1H). 26 Isomer 2: (2,2,2-trideutero)ethyl 2-(4-{[1- 1, 9, 20 and 24h 400 MHz, CDCl₃) δ: 1.65-1.91 (m, 10H), 1.91- C m/z 384 (M + H)⁺ (ES⁺),at 3.99 (1,1,1- 2.09 (m, 7H), 2.11-2.33 (m, 2H), 2.58-2.81 (m, min, UVinactive trideuteromethyl)cyclobutyl]carbamoyl}piperidin- 1H), 2.82-2.99(m, 2 H), 3.17-3.32 (m, 2H), 3.32-1-yl)-6-azaspiro[3.4]octane-6-carboxylate 3.50 (m, 2H), 4.09 (s, 2H),5.56 (br. s, 1H). 27 Mixture of diastereomers: (2,2,2- 1, 9, 21 and 24 h400 MHz, CDCl₃) δ: 1.48-2.50 (m, 13 H), 2.61- C m/z 390 (M + H)⁺ (ES⁺),at 3.70 trideutero)ethyl 2-(4-{[1-(1,1,1- 3.08 (m, 3H), 3.18-3.53 (m,4H), 4.10 (s, 2H), 5.60 and 3.84 min, UV inactivetrideuteromethyl)-2,2,3,3,4,4- (br. s, 1H).hexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylate 27 Isomer 2:(2,2,2-trideutero)ethyl 2-(4-{[1- 1, 9, 21 and 24 h 400 MHz, CDCl₃) δ:1.49-2.38 (m, 13 H), 2.98- C m/z 390 (M + H)⁺ (ES⁺), at 3.84(1,1,1-trideuteromethyl)-2,2,3,3,4,4- 3.28 (m, 3H), 3.30-3.50 (m, 4H),4.08 (s, 2H), 6.03 min, UV inactivehexadeuterocyclobutyl]carbamoyl}piperidin- (br. s, 1H).1-yl)-6-azaspiro[3.4]octane-6-carboxylate 28 Isomer 2:(2,2,2-trideutero)ethyl 2-(4-{[1- 1, 9, 19 and 24 h (400 MHz, CDCl₃) δ:1.52-2.29 (m, 19H), 2.56- C m/z 399 (M + H)⁺ (ES⁺), at 3.73(fluoromethyl)cyclobutyl]carbamoyl}piperidin- 2.81 (m, 1 H), 2.82-3.06(m, 2H), 3.17-3.51 (m, min, UV inactive1-yl)-6-azaspiro[3.4]octane-6-carboxylate 4H), 4.10 (s, 2H), 4.58 (d, J= 48, 2H), 5.67 (br. s, 1H). 29 Isomer 2: (1,1,2,2,2-pentadeutero)ethyl2- 1, 9, 11 and 25 h 400 MHz, CDCl₃) δ: 1.45 (s, 3H), 1.52-2.33 (m, 18 Cm/z 383 (M + H)⁺ (ES⁺), at 3.92{4-[(1-methylcyclobutyl)carbamoyl]piperidin- H), 2.36-3.57 (m, 8H),5.37-6.23 (m, 1H). min, UV inactive1-yl}-6-azaspiro[3.4]octane-6-carboxylate 30 Isomer 2:(1,1,2,2,2-pentadeutero)ethyl 2- 1, 9, 20 and 25 h 400 MHz, CDCl₃) δ:1.67-1.94 (m, 12H), 1.96- C m/z 386 (M + H)⁺ (ES⁺), at 3.93(4-{[1-(1,1,1- 2.06 (m, 5H), 2.10-2.32 (m, 2H), 2.59-2.74 (m, min, UVinactive trideuteromethyl)cyclobutyl]carbamoyl}piperidin- 1H), 2.82-2.94(m, 2 H), 3.21-3.31 (m, 2H), 3.31-1-yl)-6-azaspiro[3.4]octane-6-carboxylate 3.48(m, 2H), 5.55 (br. s, 1H).31 Mixture of diastereomers: (1,1,2,2,2- 1, 9, 21 and 25 h 400 MHz,CDCl₃) δ: 1.60-2.34 (m, 13 H), 2.63- C m/z 392 (M + H)⁺ (ES⁺), at 3.73pentadeutero)ethyl 2-(4-{[1-(1,1,1- 3.60 (m, 7H), 5.79 (br. s, 1H). and3.82 min, UV inactive trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylate 31 Isomer 2:(1,1,2,2,2-pentadeutero)ethyl 2- 1, 9, 21 and 25 h 400 MHz, CDCl₃) δ:1.44-2.33 (m, 13 H), 2.37- C m/z 392 (M + H)⁺ (ES⁺), at 3.81(4-{[1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4- 3.12 (m, 3H), 3.14-3.53 (m,4H), 5.56 (br. s, 1H). min, UV inactivehexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylate 32 Mixture of diastereomers:ethenyl 2-{4-[(1- 1, 9, 11 and 23 c (400 MHz, CDCl₃) δ: 1.43 (s, 3H),1.59-2.15 (m, B m/z 376 (M + H)⁺ (ES⁺), at 3.43methylcyclobutyl)carbamoyl]piperidin-1-yl}- 17H), 2.17-2.30 (m, 2H),2.56-2.73 (m, 1H), 2.77- and 3.51 min, UV inactive6-azaspiro[3.4]octane-6-carboxylate 2.97 (m, 2H), 3.27-3.54 (m, 4H),4.41 (ddd, J = 15.0, 5.0 and 1.3 Hz, 1H), 4.67-4.84 (m, 1H), 5.56 (br.s, 1H), 7.15-7.26 (m, 1H).Biological Activity

Example A

Phospho-ERK1/2 Assays

Functional assays were performed using the Alphascreen Surefirephospho-ERK1/2 assay (Crouch & Osmond, Comb. Chem. High ThroughputScreen, 2008). ERK1/2 phosphorylation is a downstream consequence ofboth Gq/11 and Gi/o protein coupled receptor activation, making ithighly suitable for the assessment of M1, M3 (Gq/11 coupled) and M2, M4receptors (Gi/o coupled), rather than using different assay formats fordifferent receptor subtypes. CHO cells stably expressing the humanmuscarinic M1, M2, M3 or M4 receptor were plated (25K/well) onto 96-welltissue culture plates in MEM-alpha+10% dialysed FBS. Once adhered, cellswere serum-starved overnight. Agonist stimulation was performed by theaddition of 5 μL agonist to the cells for 5 min (37° C.). Media wasremoved and 50 μL of lysis buffer added. After 15 min, a 4 μL sample wastransferred to 384-well plate and 7 μL of detection mixture added.Plates were incubated for 2 h with gentle agitation in the dark and thenread on a PHERAstar plate reader.

pEC₅₀ and E_(max) figures were calculated from the resulting data foreach receptor subtype.

The results are set out in Table 4 below.

TABLE 4 Muscarinic Activity pEC₅₀ M1 pEC₅₀ M2 pEC₅₀ M3 pEC₅₀ M4 (% Emaxcf. (% Emax cf. (% Emax cf. (% Emax cf. Ex. No. ACh) ACh) ACh) ACh) ACh8.33 (102)  7.82 (105)   812 (115)  8.09 (110) 1 - Isomer 1 6.49 (99) NT NT 5.99 (51) 1 - Isomer 2 7.38 (102) <4.7 (0)  <4.7 (18) 6.77 (98)2 - Isomer 1 6.48 (94)   <4.7 (14) <4.7 (7) <4.7 (11) 3 - Isomer 2 6.44(109)  <4.7 (10) <4.7 (2) 6.07 (65) 4 - Isomer 2 6.84 (111) NT NT 5.97(44) 6 - mixture of 7.36 (151)  <4.7 (13) <4.7 (5) 6.33 (54)diastereomers 7 - mixture of 7.26 (127)  <4.7 (10) <4.7 (4) 6.35 (81)diastereomers 8 - mixture of 6.96 (118) <4.7 (5) <4.7 (8) 5.77 (29)diastereomers 9 - mixture of 7.29 (142) <4.7 (6) <4.7 (5) 6.42 (66)diastereomers 9 - Isomer 1 6.52 (102) NT NT 6.23 (67) 9 - Isomer 2 7.44(100)  <4.7 (15) <4.7 (9) 6.74 (66) 10 - mixture of 6.81 (93)   <4.7(10) <4.7 (3) 6.47 (42) diastereomers 11 - mixture of 7.55 (112) <4.7(6) <4.7 (4) 6.69 (77) diastereomers 12 - racemic 7.45 (141) <4.7 (8) <4.7 (78) 7.27 (49) 13 - racemic 7.80 (139) <4.7 (7)  <4.7 (39) 7.28(44) 16 - mixture of 6.51 (113) NT NT 6.19 (56) diastereomers 18 -mixture of 6.58 (100) NT NT 6.17 (67) diastereomers 19 - mixture of 6.44(109) NT NT 5.99 (42) diastereomers 21 - Isomer 2 7.17 (107) <4.7 (9) <4.7 (12)  6.77 (111) 22 - Isomer 2 7.10 (103) NT NT 6.68 (67) 23 -Isomer 2 6.81 (90)  NT NT 6.66 (67) 25 - Isomer 2 7.27 (108)  <4.7 (23) <4.7 (17) 6.76 (83) 26 - Isomer 2 7.09 (108) NT NT  6.59 (110) 28 -Isomer 2 6.49 (120) NT NT  6.51 (106) 29 - Isomer 2 7,26 (107)  <4.7(18)  <4.7 (13) 6.73 (91) 30 - Isomer 2 7.07 (105) NT NT  6.71 (111)31 - mixture of 6.39 (110) NT NT 6.19 (77) diastereomers NT—Not tested

Example B

Passive Avoidance

Studies were carried out as described previously by Foley et al., (2004)Neuropsychopharmacology. In the passive avoidance task scopolamineadministration (1 mg/kg, i.p.) at 6 hours following training renderedanimals amnesic of the paradigm. A dose range of 3, 10, and 30 mg/kg(po) free base, administered 90 minutes prior to the training period viaoral gavage, was examined.

Example 9 Isomer 2 was found to reverse scopolamine-induced amnesia ofthe paradigm in a dose-dependent manner, with an approximate ED₅₀ of ca.10 mg/kg (po). The effect of 30 mg/kg was similar to that produced bythe cholinesterase inhibitor donepezil (0.1 mg/kg, ip) which served as apositive control (FIG. 1).

Example C

CA1 Cell Firing

Rat hippocampal slices of 400 μm thickness were cut in chilled (<4° C.)artificial cerebrospinal fluid (aCSF, composition in mM: NaCl 127, KCl1.6, KH₂PO₄ 1.24, MgSO₄ 1.3, CaCl₂ 2.4, NaHCO₃ 26 and D-glucose 10)using vibratome. Slices were maintained in oxygenated (95% O₂/5% CO₂)aCSF at room temperature for at least 1 hr prior to electrophysiologicalrecording, after which they were transferred to an interface chamber andconstantly perfused with warmed (30° C.) oxygenated aCSF at a flow rateof 1.5-3 ml·min-1. Schaffer collaterals were then stimulated (1-20 V,0.1 ms pulse width, 0.033 Hz) with a concentric bipolar electrode toevoke field excitatory post synaptic potentials (fEPSPs) recorded fromthe stratum radiatum of the CA1 region. Experiments were performed toexamine the effect of compound compared to 1 μM carbachol (CCh), on theamplitude of fEPSPs in the CA1 region of rat hippocampal slices. 1 μMCCh was initially applied until steady-state, followed by wash, beforeperforming a five point cumulative concentration-response to compound.Each compound was tested on 6 slices and results averaged. Drugpreparation; compound was dissolved in 100% DMSO at a stockconcentration of 30 mM, and diluted according to requirements,carbamoylcholine chloride (CCh) was purchased from Sigma (Cat #C4382)and dissolved at a stock concentration of 1 mM in ddH₂O.

TABLE 5 Ex. No. Cell Firing EC50 (μM) 9 - Isomer 2 5.7

Example D

Pharmaceutical Formulations

(i) Tablet Formulation

A tablet composition containing a compound of the formula (1) isprepared by mixing 50 mg of the compound with 197 mg of lactose (BP) asdiluent, and 3 mg magnesium stearate as a lubricant and compressing toform a tablet in known manner.

(ii) Capsule Formulation

A capsule formulation is prepared by mixing 100 mg of a compound of theformula (1) with 100 mg lactose and optionally 1% by weight of magnesiumstearate and filling the resulting mixture into standard opaque hardgelatin capsules.

Equivalents

The foregoing examples are presented for the purpose of illustrating theinvention and should not be construed as imposing any limitation on thescope of the invention. It will readily be apparent that numerousmodifications and alterations may be made to the specific embodiments ofthe invention described above and illustrated in the examples withoutdeparting from the principles underlying the invention. All suchmodifications and alterations are intended to be embraced by thisapplication.

The invention claimed is:
 1. A compound of the formula:

or a pharmaceutically acceptable salt thereof, wherein: X¹ and X² aresaturated hydrocarbon groups which together contain a total of five tonine carbon atoms and which link together such that the moiety:

forms a bicyclic ring system selected from the group consisting of ringsystems BA, BB, CA, and CB below:

R¹ is selected from 2-methylpropyl; 2,2-dimethylpropyl; tert-butyl;2-methyl-but-2-yl; 2,3-dimethylbut-2-yl; cyclopropylmethyl;cyclobutylmethyl; cyclopentyl; cyclopentylmethyl; 1-methylcyclobutyl;1-methylcyclopentyl; 1-methylcyclohexyl; 1-methylcyclopentylmethyl;cyclopropyl-prop-2-yl; 1-methylcyclobutylmethyl and1-ethyl-cyclobutylmethyl groups; R² is selected from hydrogen, methyl,ethyl and isopropyl; R³ is selected from hydrogen, fluorine and methoxy;and R⁴ is a C₁₋₆ non-aromatic hydrocarbon group which is optionallysubstituted with one to six fluorine atoms and wherein one or two, butnot all, carbon atoms of the hydrocarbon group may optionally bereplaced by a heteroatom selected from O, N and S and oxidised formsthereof.
 2. The compound according to claim 1 wherein R¹ is1-methylcyclobutyl.
 3. The compound according to claim 1 wherein R² ishydrogen.
 4. The compound according to claim 1 wherein R³ is hydrogen.5. The compound according to claim 1 wherein R⁴ is selected from methyl,fluoromethyl, ethyl, ethynyl and 1-propynyl.
 6. The compound accordingto claim 1 wherein the moiety

represents ring system CA:


7. The compound according to claim 1, wherein the compound is ethyl3-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-8-azabicyclo[3.2.1]octane-8-carboxylateor a pharmaceutically acceptable salt thereof.
 8. The compound accordingto claim 1, wherein the compound is ethyl3-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-9-azabicyclo[3.3.1]nonane-9-carboxylateor a pharmaceutically acceptable salt thereof.
 9. The compound accordingto claim 1, wherein the compound is ethyl2-{4-fluoro-4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 10. The compoundaccording to claim 1, wherein the compound is ethyl6-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-2-azaspiro[3.4]octane-2-carboxylateor a pharmaceutically acceptable salt thereof.
 11. The compoundaccording to claim 1, wherein the compound is prop-2-yn-1-yl6-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-2-azaspiro[3.4]octane-2-carboxylateor a pharmaceutically acceptable salt thereof.
 12. The compoundaccording to claim 1, wherein the compound is ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 13. The compoundaccording to claim 1, wherein the compound is ethyl2-(4-{[1-(1,1,1-trideuteromethyl)cyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 14. The compoundaccording to claim 1, wherein the compound is ethyl2-(4-{[1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 15. The compoundaccording to claim 1, wherein the compound is (2,2,2-trideutero)ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 16. The compoundaccording to claim 1, wherein the compound is (2,2,2-trideutero)ethyl2-(4-{[1-(1,1,1-trideuteromethyl)cyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 17. The compoundaccording to claim 1, wherein the compound is (2,2,2-trideutero)ethyl2-(4-{[1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 18. The compoundaccording to claim 1, wherein the compound is (1,1,2,2,2-pentadeutero)ethyl2-{4-[(1-methylcyclobutyl)carbamoyl]piperidin-1-yl}-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 19. The compoundaccording to claim 1, wherein the compound is(1,1,2,2,2-pentadeutero)ethyl2-(4-{[1-(1,1,1-trideuteromethyl)cyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.
 20. The compoundaccording to claim 1, wherein the compound is(1,1,2,2,2-pentadeutero)ethyl2-(4-{[1-(1,1,1-trideuteromethyl)-2,2,3,3,4,4-hexadeuterocyclobutyl]carbamoyl}piperidin-1-yl)-6-azaspiro[3.4]octane-6-carboxylateor a pharmaceutically acceptable salt thereof.